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kLiAi 


U.S. DEPARTMENT OF COMMERCE 

NATIONAL TECHNICAL INFORMATION SERVICE 


N75-32034 


FEASIBILITY STUDY OF MODERN AIRSHIPS PHASE II, VOL. Ill 
HISTORICAL OVERVIEW (TASK I) 


GOODYEAR AEROSPACE CORP . 
AKRON, OH 


AUGUST 1975 




^ 76 - 3 ^ 03 ^ 

NASA CR- 137692^3 ) 


FEASIBILITY STUDY OF MODERN AIRSHIPS 

(PHASE I) 


Volume III - Historical Overview (Task I) 


Contract NAS2-8643 


August 1975 


Prepared for 


Ames Research Center, Moffett Field, California 


by 


Goodyear Aerospace Corporation, Akron, Ohio 


Reproduced by 

NATIONAL TECHNICAL 
INFORMATION SERVICE 

US Department of Commerce 
Springfield/ VA. 22151 



FOREWORD 


This final technical report was prepared for the Ames Research Center, 
Moffett Field, Calif*, by Goodyear Aerospace Corporation, Akron, Ohio, 
under NASA Contract NAS2-8643, "Feasibility Study of Modern Airships." 
The technical monitor for the Ames Research Center was Dr. Mark D. 
Ardema. 

This report describes work covered during Phase I (9 December 1974 to 
9 April 1975) and consists of four volumes: 


Volume I - Summary and Mission Analysis (Tasks II and IV) 
Volume II -Parametric Analysis (Task III) 

Volume III -Historical Overview (Task I) 

Volume IV - Appendices 

The report was a group effort headed by Mr. Ralph R. Huston and was 
submitted in May 1975. The contractor's report number isGER-16146. 


-li- 



OVERALL TABLE OF CONTENTS 


Section Title Page 


VOLUME I - SUMMARY AND MISSION ANALYSIS 
(TASKS II and IV) 

SUMMARY 1 

RECOMMENDED PHASE II MAV/MISSION 

COMBINATIONS 2 

MAV/Mission Combination 1 2 

MAV/Mission Combination 3 3 

MAV/Mission Combination 4 5 

INTRODUCTION 6 

MISSION ANALYSIS OVERVIEW 8 

APPROACH FOR SELECTING POTENTIAL MISSIONS . 8 

PRESENT CONVENTIONAL MISSIONS 10 

Passenger and Cargo 10 

Present Conventional Passenger Missions and 

Competitive Modes 12 

Present Scheduled Airline Missions 16 

Present and Projected Passenger System 

Capabilities and Limitations 18 

Conventional Passenger MAV Mission Potential . . 23 

Present Conventional Cargo Missions and 

Competing Forms 27 

Evaluation of Present Cargo Missions to Determine 
Potentially Competitive Conventional Missions 

for MAV's 29 

Intermodal Comparisons # . 31 

Intermodal Comparisons in Price 

Competitive Market 39 

Present Scheduled Air Cargo System 

Capabilities and Limitations 45 

Conventional Cargo MAV Mission Potential .... 45 


-iii- 


Section Title Pa s e 


PRESENT UNIQUE TRANSPORTATION AND 

SERVICE MISSIONS 50 

Present Unscheduled/General Aviation 

Passenger Missions 50 

General Aircraft Fleet Composition and Use (1971) . . 52 

Fleet Composition 52 

Present Passenger Equipment Capabilities 

and Limitations 56 

Unscheduled Passenger Mission Potential 58 

Commercial 59 

Institutional Passenger 59 

Present Unscheduled/General Aviation 

Cargo Missions 60 

Present Unscheduled Cargo System 

Capabilities and Limitations 60 

Unscheduled General Cargo MAV 

Mission Potential 61 

Heavy Lift Large Indivisible Load 

MAV Mission Potential 61 

Commercial (Heavy Lift) 62 

Institutional (Heavy Lift) 63 

Agricultural Transportation MAV 

Mission Potential 63 

Platform/Service Mission Potential 65 

Commercial (Platform/Service) 66 

Institutional (Platform/Service) 67 

Resources from Remote Regions - MAV 

Mission Potential 69 

Military MAV Mission Potential 71 

MAV SYSTEM PERFORMANCE AND OPERATIONAL 
REQUIREMENTS FOR POTENTIAL MISSIONS 74 

General 74 

Scheduled and Unscheduled Civil Passenger and 

General Cargo Transportation Missions 86 

Unique Missions 86 

Military Missions 87 

EVALUATION OF MAV’s FOR POTENTIAL MISSIONS AND 
SELECTED MISSION PECULIAR FIGURES OF MERIT . . 89 

General 89 

Potential Conventional Passenger and 

Cargo Missions 97 

Potential Unique Missions and Selected 

Mission Peculiar Figures of Merit 98 

Potential Military Missions and Selected Military 

Mission Peculiar Figures of Merit 101 


-iv- 


Section 


Title 


Page 

POTENTIAL MISSIONS BY VEHICLE SIZES AND TYPES . 103 

General 103 

Civil Missions 103 

Military Missions 107 

EVALUATION AND SELECTION FACTORS 109 

Missions 109 

Parametric Analysis 109 

Selected Combinations 110 

MAV/Mission Combination 1 Ill 

MAV/Mission Combination 2 115 

MAV/Mission Combination 3 116 

MAV/Mission Combination 4 120 

PHASE II RECOMMENDATIONS 123 

REFERENCES 123 

VOLUME II - PARAMETRIC ANALYSIS 
(TASK III) 

SUMMARY 1 

INTRODUCTION 2 

BACKGROUND 2 

OBJECTIVES 4 

SCOPE 4 

GENERAL APPROACH 5 

METHODS OF ANALYSIS 6 

PARAMETRIC STUDY OVERVIEW 10 

CONVENTIONAL AIRSHIPS 11 

Design Description (Conventional Rigid) 11 

Pressurized Metalclad 16 

CONVENTIONAL AIRSHIP AERODYNAMICS ANALYSIS . . 20 

PROPULSION ANALYSIS (PERFORMANCE) 21 


- v- 



Section Title Page 


PROPULSION SYSTEM WEIGHTS ANALYSIS 22 

STRUCTURAL WEIGHTS ANALYSIS 22 

CONVENTIONAL AIRSHIP PARAMETRIC ANALYSIS ... 28 

Introduction z 8 

Fineness Ratio Tradeoff Study 31 

Metalclads, 1 /d Optimization Study 34 

Conventional Airships Heaviness Tradeoff Studies 

Based on UL*Vc/EW 40 

Conventional Airship Heaviness Optimization Study 
Based on Payload Ton-Mile per Hour as a 

Function of Range 42 

Conventional Airship Heaviness Tradeoff 

Study Results 56 

Advanced Ellipsoidal Airship Concepts 66 

PARAMETRIC ANALYSIS OF HYBRID VEHICLES .... 68 

Overview 68 

Preliminary Configuration Evaluation 69 

Modified Delta Planform Hybrid (Selection 

Rationale and Configuration Description) 71 

Structural Description 74 

Delta Planform Hybrid Aerodynamics Analysis .... 78 

GASP Aerodynamics Estimating Procedures 79 

Propulsion 80 

Structural Analysis and Weights Analysis 80 

Hybrid Parametric Analysis 89 

Hybrid Parametric Performance Results 94 

Lifting Body Hybrid/Ellipsoidal Airship 

Productivity Comparison 102 

HEAVY LIFT HYBRID VEHICLE CONCEPT 107 

Heavy Lift Performance versus Gross Weight: 

Size Limitations and Scale Effects Ill 

Alternate Figure of Merit for Conventional Airships . . 114 

Fuel Efficiency Considerations 115 

Endurance Capability 118 

Range Capability 119 

Comparison with Historical Results 119 

PARAMETRIC ANALYSIS SUMMARY AND CONCLUSIONS . 123 

Conventional Airship/Lifting Body Hybrid 124 


Section Title Page 


LIMITATIONS OF CURRENT STUDY 125 

REFERENCES 129 

VOLUME III - HISTORICAL OVERVIEW 
(TASK I) 

SUMMARY 1 

INTRODUCTION 2 

PARAMETERIZATION OF DESIGN CHARACTERISTICS . 8 

Rigid Airships 8 

Non-rigid Airships ZZ 

Semi-rigid Airships 32 

Analysis of Data (Rigid, Non-rigid, Semi-rigid) ... 35 

HISTORICAL MARKETS, MISSION COSTS, AND 

OPERATING PROCEDURES 45 

General 45 

Operations and Economics 46 

Manufacturing 63 

Prior Goodyear Economic Studies (1944 $) 72 

American Military Experiece (1916 to 1961) .... 72 

Airship Safety 86 

CRITICAL DESIGN AND OPERATIONAL 

CHARACTERISTICS 94 

General 94 

Maximum Bending Moment Criteria 104 

Operational Aspects of Airships 109 

STATE OF THE ART 116 

Rigid Airships (Materials) 116 

Material Life Characteristics 124 

Non-rigid Airships (Materials) 125 

Rigids (Economically) 126 

Operational Aspects of Conventional MAV's .... 129 

Recent LTA/HTA Vehicles and Concepts 134 

REFERENCES 143 


- vii- 




VOLUME IV - APPENDICES 


Appendix Title Page 

A (1) General Dimensions and Characteristics of French 

Dirigibles A-l 

(2) Characteristics of Italian Semi- rigid Airships . . . A-l 

B Non-rigid Airships Manufactured by Goodyear B-l 

C (1) Properties of 7050 Aluminum Alloy C-l 

(2) Macon Gas Cell Data C-l 

(3) Additional Chronological History of German 

Airship Events C-l 

D Derivation of Conventional Ellipsoidal Airship Structural 

Weight Estimating Relationships • . D- 1 

E Aerodynamics Analysis E-^l 

F Propulsion and Take Off Analysis F-l 

G Sandwich Monocoque Rigid Airship G*1 

H Design Options H- 1 

I Configuration Screening Exercise 1*^1 



LIST OF ILLUSTRATIONS (VOLUME III ONLY) 


Figure Title Page 

1 Typical Rigid Airship 4 

2 Typical Non- rigid (Pressure) Airship 6 

3 Typical Semi-rigid Airship 8 

4 Characteristics of German Zeppelin and Schutte-Lanz 

Rigid Airships 17 

5 Summary of Significant Rigid Airship History 23 

6 Useful Lift-to-Gross Lift Ratio vs Airship Volume (Past 

Rigid Airship Configurations) 35 

7 Empty Weight-to-Gas Volume Ratio as a Function of Gas 

Volume (Past Rigid Airship Configurations) 38 

8 Useful Lift-to-Gross Lift Ratio versus Airship Volume 

(Past Non-rigid and Semi-rigid Configurations) 39 

9 Comparison of Past Rigid, Non-rigid, and Semi-rigid Air- 
ship Configurations 40 

10 Altitude versus Useful Lift 42 

11 Rigid Structural Weight versus Airship Air Volume ... 43 

12 Payload Ton-Miles per Hour versus Gross Weight (Rigids) 44 

13 Payload Ton-Mile s/(Hour) (Empty Weight) versus Gross 

Weight (Rigids) 45 

14 Utilization Rate as a Function of Stage Length for German 

Commercial Service (1910 to 1937) 51 

15 Average Block Velocity Maximum Velocity Ratio .... 52 

16 Fare Schedule for Graf Zeppelin and Hindenburg (1936$) * 56 

17 Direct Construction Man-Hours for Past Rigid Airships 

(First Unit of New Design) 68 

18 Manufacturing Costs for Non-rigid Airships (Prototype). . 71 

-ix- 



LIST OF ILLUSTRATIONS (VOLUME III) (CONTINUED) 


Figure Title Page 

19 Manufacturing Costs for Non- rigid Airships (Production). . 71 

20 1944 Operating Cost Comparison for Various 

Forms of Air Transport 78 

21 Safety Statistics for Airships and Airplanes 93 

22 General Distribution of Forces on Airship 96 

23 Investigation of Gust Forces by Water Model Tests .... 100 

24 Structural Model Tests 102 

25 Comparison of Theoretical Calculations with Test Results. . 103 

26 Estimated Variation of Peak Bending Moment Coefficient 

with Fineness Ratio, C = M/qV 108 

2 7 Comparative Aerodynamic Bending Strength of 

Different Airships 110 

28 Preliminary Estimate of Price versus Empty Weight for 

Conventional Rigid Airships 128 

29 Automatic Flight Control System Schematic 131 

30 Goodyear Mayflower Stern Propulsion Demonstration . . . 140 


-x- 


LIST OF TABLES (VOLUME III ONLY) 


Table Title Page 

1 Characteristics of German Zeppelin Rigid Airships LZ-I 

Through LZ-1Z1 (References 1 and Z) 9 

Z German Schutte-Lanz Airships (Rigid) 15 

3 Characteristics of Rigid Airships (References 3, 4, and 5) . 19 

4 Detailed Weights for Notable Rigid Airships (Reference 6) . ZO 

5 German Non-rigid Airships (Reference 1) 24 

6 American Non-rigid Airship Characteristics Z5 

7 ZMC-Z Characteristics (Reference 7) Z7 

8 Comparison of Akron (ZRS-4) and Proposed 

MC-7Z Metalclad 28 

9 Structural Weight (Pounds) of Akron and MC-74 

(Reference 9) 29 

10 Principal Characteristics and Approximate Weights of 

Ultimate Airship (1939) by Burgess (Reference 10) 31 

11 Detailed Weights for ZPG-3W With and Without 

Military Equipment (Reference 13) 33 

12 Characteristics of German Semi-rigid Airships 

(Reference 1) 34 

13 Characteristics of RS-1, Roma, and Norge Semi-rigid 

Airships (Reference 3) 36 

14 Selected World War I German Bombing Raids 47 

15 Luftschiffbau Zeppelin Commercial Service (1910 to 1937). . 49 

16 Data Relative to Graf Zeppelin Transoceanic Flights and 

Passenger Load Factors 54 

17 Summary of Hindenburg's 1936 North Atlantic Service 

(Westward Crossings ) 58 


-xi- 



LIST OF TABLES (VOLUME III ONLY )( CONTINUED) 


Table 

Title 

Page 

18 

Summary of Hindenburg's 1936 North Atlantic Service 
(Eastward Crossings) 

59 

19 

Zeppelin Commercial Passenger Service Operating Costs . 

61 

20 

Detailed Breakdown of Actual Akron and Macon Project 
Hours and Dollars (As of Date Incurred). 

64 

21 

Summary of Rigid Airship Manufacturing Data 

66 

22 

Fabrication Costs for Non-rigid Airships . . 

69 

23 

Engineering Hours Breakdown 

73 

24 

Cost of Six 10, 000, 000 - Cu Ft Airships (1944 

73 

25 

Materials and Material Strengths (Rigids) 

117 

26 

Technical Details of Proposed (and Existing) Willlenkamper 
Non-rigid Airships 

142 


-Xll- 


FEASIBILITY STUDY OF MODERN AIRSHIPS 


VOLUME III - HISTORICAL OVERVIEW (TASK I) 
Gerald L. Faurote* 

Goodyear Aerospace Corporation 


SUMMARY 


The history of lighter-than-air (LTA) vehicles is reviewed in terms of 
providing a background for the mission analysis and parametric analysis tasks 
(see Volumes I and II, respectively), which were performed as part of the 
Goodyear Aerospace Corporation (GAC) feasibility study of modern airships. 
In addition, data from past airships and airship operations are presented that 
will be of interest in Phase II. 

The following areas are detailed relative to past vehicles and operations: 

1. Parameterization of design characteristics 

2. Historical markets, missions, costs, and operating procedures 

3. Indices of efficiency so that comparisons can be made from 
the parametric analysis of Volume II 

4. Identification of critical design and operational characteristics 

5. Definition of the 1930 state of the art, both technically and 
economically. A 1974 state of the art is defined from both a 
technical and an economic standpoint. 


As a final portion of the historical overview, the more prominent concepts 
emerging in the current resurgent interest in LTA are briefly reviewed. 


^Development engineer, Goodyear Aerospace Corporation, Akron, Ohio , 


- 1 - 



INTRODUCTION 


The essentials of free ballooning - including the gas-tight bag, the valve, 
the net, and the basket that carried the pilots - were all developed in Europe 
in the 18th century. Benjamin Franklin saw One of these earliest flights 
and wrote home to friends in America: ''Among the pleasantries that conver- 

sation produces on this subject, some suppose flying to be now invented, and 
that since men may be supported in the air, nothing is wanted but some light 
handy instrument to give and direct motion. " 

Inventors worked for a century to verify Franklin’s prophecy. In 1852, 
Henri Giffard, a French inventor, built the first power-driven balloon, a 45- 
ft-long dirigible*, which derived its motive power from a three -horsepower 
steam engine. The first rigid airship was constructed in 1898 by an Austrian 
named Schwartz. He used a framework consisting of 12 rings and 16 longi- 
tudinal aluminum girders and an outer covering of sheet aluminum. 

At the turn of the century, Count Zeppelin completed and flew his first 
craft and thus laid the foundations for practicable commercial and military 
operations. Between 1900 and 1918, the German Zeppelin Company built more 
than 100 rigid airships. Ultimately, the Zeppelin Company built and operated 
two of the world's most notable airships, the Graf Zeppelin and the Hinden- 
burg, the latter being the largest airship ever built. 

Other notable airship constructors from 1900 to 1918 were the German 
Schutte-Lanz Company, which built 22 rigid airships from 1911 to 1918, and 
the German Luft-Fahrying -Gesellschaft Company, which built 27-Parseval- 
type non-rigid airships from 1906 to 1918. The Prussian Army Airship Works, 

also a German concern, manufactured about 10 semi-rigid airships, the ma- 
jority of them for the Prussian Army. 


A lighte r-than-air aircraft, having its own motive power, that can be steered in 
any desired direction by its crew. Dirigible: of aircraft or airborne devices 
that can be directed or steered; dirigible balloon; a balloon, especially a non- 
spherical balloon, that can be steered. No specific structural type is implicit 
in the term "dirigible" in the U.S. Air Force Dictionary (1956) 


- 2 . 




The British became interested in rigid airships about 1910 and built a 
small ship, the Mayfly* After 1914, the British also became highly active in 
building non-rigid airships. The British R-100 and R-101 attest to their con- 
tinued interest in the rigid design. Both France and Italy were active in build- 
ing semi-rigid airships, the Roma and Norge being notable Italian configura- 
tions . 

The American airship industry started in 1911, with Goodyear and Good- 
rich the principal early suppliers. During World War I, Goodyear became 
the major supplier and ultimately built and delivered more than 1000 balloons 
and close to 100 non-rigid airships for the United States, England, and France. 
Construction activities continued at Goodyear after the war, including build- 
ing America's first semi-rigid ship, the RS-1. 

In 1924, the Inter-Allied Air Commission forbade further German Zep- 
pelin Company operations. With dismantling the huge zeppelin hangars on 
Lake Constance projected, The Goodyear Tire & Rubber Company agreed 
with Luftschiffbau -Zeppelin to form a new company, Goodyear Zeppelin Corp- 
oration, in which L-Z would have a one -third interest and GT&R two -thirds 
interest and in which the Zeppelin patents could be used. Dr. Karl Arnstein, 
chief engineer of Euftschiffbau-Zeppelin - along with 12 of his technical ex- 
perts - came to Goodyear to assume the position of Vice-President of 
Engineering. With the combined expertise of the German Zeppelin Company 
and the American airship industry now available, the Goodyear Zeppelin 
Company a few years later designed and built the rigid airships Akron and 
Macon for the U. S. Navy - the largest airships built to that date. 

The Goodyear Zeppelin Company, later renamed Goodyear Aircraft 
Company and known today as Goodyear Aerospace Corporation, continued to 
build non-rigid airships for military purposes and between 1941 and 1961 de- 
livered nearly 220 units to the Navy.* In 1961, the last ZPG-3W airship - the 

largest non-rigid ever built - was delivered to the U. S. Navy. Goodyear 
Aerospace continues to build advertising airships today for its parent organi- 
zation, The Goodyear Tire & Rubber Company. 

-------- _ 

Only supplier of airships to the Navy since 1930. 


3 - 



The conventional airship is a powered, streamlined body-of-revolution, 
air-displacement vehicle that derives its buoyancy from the difference in weight 
of the inflation gas within its hull or envelope and the weight of the ambient 
atmosphere thus displaced. Historically, two distinct structural types of air- 
ships have given rise to a definition of dirigibles based on these structural 
differences: (1) rigid (unpressurized) airships and (Z) non-rigid (pressurized) 

airships. A third type, the semi-rigid, basically is a blend of these two. 

The rigid type (see Figure 1) - such as the Akron, Macon, and Hinden- 
burg - were built of aluminum bulkhead rings, aluminum transverse girders, 
and a network of pretensioned diagonal shear wires. An outer fabric (doped 



Figure 1 - Typical Rigid Airship 


- 4 - 



cotton cloth) provided a wind and weather cover. The lifting gas was contained 
in several independent gas-tight cells, which were supported between bulkhead 
ring nettings. The gas cells were partially filled at sea level, with pressure 
height being the altitude at which expansion of the gas completely filled the 
cells. Climb beyond pressure height, which normally was not undertaken, 
necessarily required valving and irrevocable loss of the lifting gas to prevent 
overpressuring and rupturing the cells. Generally, poppet valves with spring 
settings for overpressure protection provided automatic pressure valving at 
the pressure height with a manual capability also available. Both hydrogen 
and helium have been used as lifting gases, with the latter much preferred be- 
cause of its inert character. Heavy takeoffs* were never accomplished with 
rigid airships . 

The rigid airships manufactured by the German Schutte-Lanz Company 
used wood exclusively for structural members. During 1911 to 1917 and even 
prior to this, the German Zeppelin Company used aluminum in its rigid air- 
ships. The first rigid also was of an aluminum construction. It is not exactly 
clear why the Schutte-Lanz Company chose wood, but at the time of the World 
War I armistice the company was preparing to use aluminum in future con- 
struction. 

The non-rigid (pressure) airship (see Figure 2) consists of a hull or en- 
velope typically of a coated fabric filled with a lifting gas and pressured slightly 
above ambient. Earlier non-rigid envelopes were coated cotton fabric while 
the more recent configurations such as the ZPG-3W used a neoprene -coated 
dacron. Dacron has a higher strength-to-weight ratio than cotton. 

In the non-rigid, several ballonets - or air compartments - are curtained 
off within the envelope. They normally are located forward, aft, and amid 
ship. The maximum ballonet capacity is a function of the design pressure 
height. The envelope is pressurized by ducting air for the ballonets from 
the propwash or pumping with electric blowers through an air distribution 
system to the ballonets. Dampers, air lines, and exhaust valves at the 


Heavy takeoff denotes aerodynamic lift in addition to aerostatic lift required 
to accomplish takeoff. 


- 5 - 



CAR PASSENGER 
COMPARTMENT 


ENGINE 


Figure Z - Typical Non-rigid (Pressure ) Air ship 


ballonets permit the envelope pressure to be controlled, and relative fullness 
of the fore and aft ballonets permit trimming in pitch. As the ship ascends, the 
lifting gas is expanded without gas being lost by deflation of the ballonets. 
Pressure height is the altitude at which the ballonets are completely deflated, 
the envelope at that point being 100 percent full of lifting gas. Further ascent 
can occur only with valving of the lifting gas. It is possible for anairship tobe 
flown so high, with consequent valving of the lifting gas, that upon descent the 
ballonets are pumped full (of air) before the ground has been reached. At this 
point, the airship can descend with envelope pressurization only by pumping 
air directly into the lifting gas provided an emergency access route of air to 
the lifting gas is available. Both hydrogen and helium have been used as a 
lifting gas. 

Rate of ascent with a pressure airship may be limited by engine power if 
the ship is "heavy” but is structurally limited by the ballonet valves 1 capacity 
to exhaust air. Conversely, rate of descent is limited by the air system's 
capacity to pump air into the ballonets as the helium contracts with increasing 
ambient pressure. 


- 6 - 



While the car structure and engine nacelles on a rigid airship are extended 
from convenient bulkhead rings and longitudinal girders, the car structure 
weight on a non-rigid is distributed to the fabric envelope by catenary systems. 
Usually, two identical internal catenary curtains, either side of the centerline 
on the top of the envelope, tie to the upper envelope along two fore and aft Y 
joints. Vertical tension cables from the roof of the car carry the weight to 
fitting points on the curtains. The curtains spread the load to the upper en- 
velope, deforming it slightly "out-of-round" at the Y intersection. A catenary 
system around the car -lower envelope intersection distributes pitching or 
yawing loads to the envelope. Fins on a non-rigid are cable -braced to finger 
patches tangent to the cable -envelope intersections. Powerplant installations 
on a non-rigid always have been extensions from the hard car structure. 

Pressurized metalclad airships have been considered throughout the 
history of L.TA. The metalclad, as the name suggests, uses a thin metal 
covering (historically, only aluminum was ever seriously considered) 
rather than the conventional fabric covering. 

The semi-rigid airship (see Figure 3) generally differed from the non- 
rigid by using a nose -to -tail rigid keel rather than the catenary curtains for 
distributing the car weight into the fabric envelope. It was still a pressure 
airship and required slight pressurization to permit resistance of hull bend- 
ing moments without envelope wrinkling. Its cross-sectional shape tended 
more to a pear shape because the entire car weight was applied to the bottom 
of the envelope. 

The following subsections of the historical overview relate to: 

1. Parameterization of design characteristics for both 
conventional and unconventional LTA vehicles of 
interest to the current study. 

2. Results of historical markets and missions, costs 
and operating procedures, and research relative to 
past LTA activities. 


- 7 - 



Pressure semi-rigid 


Figure 3 - Typical Semi-rigid Airship 


3. Parameterization of the data presented in Item 1, 
above, into the indices of efficiency of interest to the 
current study. 

4. Identification of critical design and operational charac- 
teristics of past LTA vehicles. 

5. Definition of 1930 state of the art (SOA), technically and 
economically, relative to LTA vehicles. 

6. Definition of 1974 SOA, technically and economically, 
relative to LTA vehicles. 


PARAMETERIZATION OF DESIGN CHARACTERISTICS 

Rigid Airships 
Ge rman 

Tables 1 and 2 give the more important characteristics of all German air- 
ships built up to and including 192 0, except for a few built prior to 1910 that 
fall under miscellaneous types. These airships are omitted because of their 

— 8 — 



TABLE 1 - CHARACTERISTICS OF GERMAN ZEPPELIN RIGID AIRSHIPS 
LZ-1 THROUGH LZ-121 (REFERENCES 1 AND 2) 


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Jan 17, 1906 

Autumn 1913 
Aug 5, 1908 
Apr 25. 1910 

Sep 19, 1910 
Jun 28, 1910 

May 16. 1911 

Aug 1, 1919 
Jun 28, 1912 

Autumn 1915 

Summer 1914 

Summer 1916 
Sept 9, 1913 
Mar 19, 1913 
Autumn 1916 

Autumn 1916 
Oct 17, 1913 

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Jul 2, 1900 

Nov 30, 1905 
Oct 9, 1906 

Jun 20, 1908 
May 26. 1906 
Aug 25, 1909 

Jun 19, 1910 
Mar 30, 1911 
Oct 2, 1911 

Jun 26, 1911 
Feb 19, 1912 
Apr 25, 1912 

Jul 30, 1912 
Oct 7, 1912 
Jan 16, 1913 
Mar 19, 1913 

May 3, 1913 

Sep 9, 1913 

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About 
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About 

13,200 

13,200 

About 

13,600 

13.200 

13,600 

18.900 

15.500 

15.900 

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15.900 

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27,200 

27,200 

27.200 

29.200 

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36 , 000 

36.000 

38.200 

46.500 

96.500 

40.200 
42,700 

42.700 

44.700 

42.700 

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53.700 
46,600 
46,600 
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50.000 

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430.000 

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562.000 

680.000 
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592.000 

628.000 

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76,800 

76,800 

76,800 

76,800 

76,800 

76,800 

76,800 

76,800 

76,800 

76,800 

76.800 

85.800 

76.800 
76,800 
76,800 
76,800 

76.800 

85.800 

76.800 

85.800 

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1,128,000 

1,128,000 

1,128,000 

1,128,000 

1,128,000 

1,128,000 

1,128,000 

1,262,000 

1,128,000 

1,128,000 

1,128,000 

1,128,000 

1,128,000 

1,262,000 

1,128,000 

1,262,000 

1,228,000 

1,262,000 

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ORIGINAL PAGE S 
OF POOR QUALITY 


- 11 - 



TABLE 1 - (CONTINUED) 



12 



TABLE 1 - (CONTINUED) 


I 


3a*odox»A» 

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Oct 8, 1920 
Dec 29, 1916 
Oct 20, 1917 

Mar 17, 1917 
Jan 5, 1918 

Jun 17, 1917 

Oct 20, 1917 

July 1919 
Jun 14, 1917 
Oct 20, 1917 

Jan 5. 1918 

Jun 17, 1917 
Oct 20, 1917 

Jan 5, 1918 
Auguit 1919 

Jul 19, 1918 

Aug 11, 1918 
Oct 20, 1917 

3i4TJ - 9JWQ 

Nov 1, 1916 

Feb 22, 1917 
Nov 22, 1916 
Apr 2, 1917 

Dec 11, 1916 
May 1, 1917 

Jan 3, 1917 

Jun 9, 1917 

Jan 31, 1917 
Feb 21, 1917 
Mar 6, 1917 
Apr 1, 1917 

Apr 24, 1917 

May 22, 1917 
Jun 13, 1917 

Jul 6, 1917 
Jul 4. 1917 

Aug 13, 1917 

Aug 18, 191? 
Sep 1, 1917 

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132,000 

132,000 

132,000 

132,000 

132,000 

132,000 

132,000 

132.000 

133.000 

133.000 

134.000 

134,000 
134,000 
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134,000 

134,000 

134,000 

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1,940,000 

1,940,000 

1,940,000 

1.940.000 

1.960.000 

1.960.000 

1.970. 000 

1,970,000 

1,970,000 

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OF POOR QUALITY! 


13 


TABLE 1 - (CONTINUED) 






















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3.7 

8.5 

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Jul 17, '13 

Jan 10, 16 

Hay 1, 16 
Dec 15, 15 

Jul 5, 15 

Nov 18, 15 
Mar 6, 17 

Nov 20, 17 
Mar 30, 17 
Jul 28, 16 

Sept 3 16 
Dec 28, 16 
Feb 8, 17 

May 11, 17 
Summer 17 

Summer 17 
Summer 17 
Feb 8, 17 

3q8lld 

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Oct. 17, 11 
Feb 28, 14 

Feb 4, 15 
Apr 25, 15 

Jun '15 

Sept 19,15 
Sept 3, 15 

Mar 30, 16 
May 24, 16 
May 17, 16 

Aug 2, 16 
Nov 9, 17 
Oct 19, 16 

Aug 23, 16 
Nov 9, 16 

Jan 18, 17 
Mar 22, 17 

‘paadg 

44.0 

55.0 

52.5 

53.0 

51.5 

57.5 

56.0 

57.5 

57.5 

56.0 

57.0 

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About 

56.0 
56.0 

56.0 

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720 

840 

840 

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240 

180 

210 

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9,900 

17.000 

23.000 

29.000 
30,700 

31,400 

34.800 

34.200 

41.100 
43,600 

46.200 

About 

46,200 

45.800 
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44.000 
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45.100 

45,100 

45,100 

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49,200 

60,000 

65.800 

77.800 
77,800 

77,800 

84 , 500 
84,500 

84 , 500 

84,500 

93,300 

93,300 

93,300 

93,300 

93,300 

93,300 

93,300 

93,300 

93,300 

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60.3 

59.7 

59.7 

64.8 
64.8 

64.8 

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- 15 - 






















relative unimportance, since they cannot be classified as successful or import- 
ant in influencing the development of German airships. From this data. Figure 
4 has been prepared to show the technological evolution of both the Zeppelin 
(rigid) and Schutte-Lanz (rigid) airships during this period. 

At the extreme top of Figure 4, the year the first airship of a particular 
Zeppelin type appeared and the L-Z number of that ship are given. Type let- 
ters assigned to the various classes of ships are given in the third heading at 
the top of the figure. Where several types include airships that have differ- 
ent characteristics, these types have been plotted separately on each curve 
(see H, H', H P, P 1 ; and R, R', and R " ). For instance, airships H, H', 
and H" are the same particular letter type, but they had to be plotted separ- 
ately since their characteristics varied and showed development within the 
type. The designation of the Schutte -Lanz airships is included with the various 
plots . 

Curve A of Figure 4 shows the improvement that occurred in the impor- 
tant useful load -to -total load (gross weight) index. Improvement in the Zep- 
pelins from a 20 percent factor in 1900 to a 65 percent factor at the close of 
World War I represented a very substantial improvement. Later airships, 
German Zeppelins included, did not have useful load-to-gross weight ratios 
approaching the 65 percent factor of the earlier Zeppelins. The early Zep- 
pelin airships had higher useful load-to-gross weight ratios for the following 
reasons : 

1. They were designed to much less severe strength criteria, 
especially with regard to aerodynamic loads on the hull 
and tail surfaces. 

2. They carried no electronic gear except a small radio. 

3. Crew accommodations were extremely meager. 

4. They carried no landing gear to speak of, no hydraulic 
systems, no bow mooring, and no power boost for control. 

5. Their gas valve complement permitted a rate of ascent 
of only 6 meters per second. 

Curve B of Figure 4 indicates that maximum speed capabilities rose from 
8.94 to 37. 01 m/s (20 to 82.8 mph), with more than half this increase occurring 


- 16 - 



DATE 1900 ’05 *08 ’09 *10 *11 *12 
LZ NO .1 i 2 4 6 7 9 11 

TYPE A A BB* C DD* E FF* G 


12* 

13* 

13’ 

14' 

14' 

14' 

15* 

15* 

14 

18 

21 

22 

24 

26 

36 

38 

HH’ET I 

K 

1» 

M 

N 

O 

PP' 


15* 16* 17* 17* 17* 17* 17* 18' 19* 

59 62 91 92 95 100 102 112 120 

Q R R*R" S T U VV W X yy 



WATTS, 1.0 mph = 4.470 x 10" 1 m/s 


Figure 4 - Characteristics of German Zeppelin and 
Schutte-Lanz Rigid Airships* 


between 1914 and 1918. Accompanying this increase in speed was a similar 
increase in horsepower. The increase in horsepower is shown in Curve C in 
horsepower per 1000 cu ft. Curves B and C show that, when airship type R 
is compared with types S, T, U, and V, better aerodynamic efficiencies are 
obtained for the latter configurations. 


. 17 - 




Curve D shows the increase in horsepower that resulted in the increase 
in speed portrayed in Curve B. Curves E, F, and G show the general evolu- 
tion to larger capacity ships, with increases in both diameter and length oc- 
curring. Curve H shows the number of gas cells as a function of airship type. 
Curve I depicts the number of each type of airship built. 

General data and characteristics relative to the two most notable German 
airships, the Graf Zeppelin and Hindenburg, have been included in Table 3, 
which lists all major rigid airships. Table 4 gives a detailed weight breakdown 
of these two German airships and the other notable rigids. 

B ritish 

The designers of Vickers Limited produced Britain's first rigid airship 
for the British Navy in 1911 . This ship had a 19, 994 cu m (706, 000 cu ft) 
capacity, was framed of aluminum and incorporated swiveling propellers, and 
had water recovery apparatus and mooring mast provisions. This ship was 
wrecked through inexperience in ground handling, which resulted in halting all 
rigid airship development in Britain. 

In 1913, the admiralty again contracted for another rigid airship from 
Vickers. After ordering work on it suspended once in 1914, the airship R-9 
was finally completed and successfully flown in April 1917. The R-9 had a 
32, 656 cu m (800, 000 cu ft) capacity and was used extensively in training crews 
and developing the swiveling propellers and mooring mast inventions. The R-9 
established the "23" class airships, and several 25,488 cu m (900,000 cu ft) 
airships were built. 

The "33" class rigid airships built by the British took the name from the 
German airship L-33 (brought down in Scotland in 1916) and were directly 
copied from it. These ships had a 56, 640 cu m (2, 000, 000 cu ft) capacity, and 
one of them (the R-34) made the Trans -Atlantic flight to New York in May 1919. 
The class "33" airships were the only successful rigids the British ever built, 
and their success is reportedly due to the Zeppelin design. 

The next attempt, a much larger ship - the R-38, was lost with all hands 
in 1921 and stopped the airship program for another eight years, at which 
time Britain designed and built the R-100 and the R-101. 


- 18 - 


TABLE 3 - CHARACTERISTICS OF RIGID AIRSHIPS (REFERENCES 3,4, and 5)* 



r A\ 


entirely aerostatic in that "heavy" take offs were not utilized; Lift of helium at 59°F, 29.92 in : 

purity is used and is 0.062 lbs/ft 3 ; corresponding lift for hydrogen is 0.068 lbs/ft 3 ; fuel gas is 

50 knots 

Total gas volume (2,800,000 cubic ft. was H 2 ); 1,100,000 was fuel gas) 

Minus airplane compartment of 2664 Kg 





TABLE 4 - DETAILED WEIGHTS FOR NOTABLE RIGID AIRSHIPS (REFERENCE 6)* 





95 percent inflation with gas and lift given in Table 



These ships had a 144, 432 cu m (5, 100, 000 cu ft) capacity and a radical 
design that used a few heavy longitudinal members instead of many light 
stringers. The outer covering was unstable in the large flat areas between 
these members and had to be pulled inward, which gave the ship a peculiar 
fluted effect. This also limited the gas capacity and reputedly resulted in an 
overweight design. 

Great Britain finally discontinued further rigid airship development after 
the R- 101 was lost in a flight across France; the flight was started immediately 
after an extra bay for increased lift had been added. The evidence brought for- 
ward by the court of inquiry investigating the crash disclosed that the lift still 
was not favorable and that the cell wires were slackened to further increase 
volume before the last flight, which permitted the cells to chafe on the longitudi- 
nal girders. The airship crashed due to a sudden loss of lift. The R-100 was 
scrapped shortly after the loss of the R-101, thus ending Great Britain’s rigid 
airship efforts . 

Table 3 compares the British R-34, R-38, R-100, and R-101 with the 
other rigid airships of major interest. 


Ame rican 

American rigid airship programs started with the launching of the Shen- 
andoah from Lakehurst Naval Air Station in 1923 and with a research project 
in 1922, which was to result in the ZMC-2 metalclad airship. 

The most notable American rigid airships were the Akron and Macon. 
Table 3 compares the general characteristics of these airships with other 
notable rigid airships. Table 4 compares the detailed weight breakdown of 
the Akron and Macon (Macon data presented) with detailed weight breakdowns 
of other notable rigids. 

Extensive technical data, analysis, design information, and test results 
are available at Goodyear relative to the Akron and Macon airships but seem- 
ingly are not of general interest and accordingly are not included in this his- 
torical overview. Should any of this data be used subsequently, it will be 
presented at that time. 

‘'Akron was slightly heavier. 


- 21 - 


Figure 5 summarizes the development of the rigid airship and shows that 
various rigid airship projects have continued at Goodyear. The detailed weight 
breakdown resulting from extensive design and cost analyses conducted in the 
mid- 1940‘s by Goodyear relative to a 2 83, 2 00 cu m (10 million cubic foot) air- 
ship for both passenger and cargo transportation is included in Table 4. 

Non-rigid Airships 
German 

Table 5 summarizes the characteristics of the major German non-rigid 
airships, which were all constructed prior to or during World War I. The 
Wullenkemper organization has recently designed and built non-rigid airships. 

F rench 

Appendix A of Volume IV summarizes the characteristics of several 
French non-rigid airships. 


British 

Although the British preceded the United States to some extent in the de- 
velopment of non-rigid airships, there appears to be no significant differences 
in the configurations; thus, British data are not presented. 

Ame rican 

America, by far, has been the major builder of non-rigid airships and, 
with minor exception, the only builder of them since the close of World War I. 
Appendix B of Volume IV summarizes the non-rigid airships manufactured by 
Goodyear, which has been the major supplier. Table 6 summarizes the charac- 
teristics of various types of American non-rigids. 

Another American non-rigid airship of interest is the metalclad ZMC-2 
built by the Aircraft Development Corporation for the Navy. The character- 
istics of this configuration are also summarized in Table 6, with added detail 
in Table 7. As pointed out in several references to the ZMC-2, it does not 
compare favorably with the conventional construction because for smaller sizes 
the minimum gage restriction relative to the thickness of the metal covering 
severely penalizes the metalclad. 


-22 



1900 1910 1920 1930 1940 1950 1960 1970 













TABLE 5 - GERMAN NON-RIGID AIRSHIPS (REFERENCE 1 ) 


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ORIGINAL PAGE 18 
- 24 - OF POOR QUALITY 


PL-22-23-24 Never Conipleted 

1.0 ft = 3. 048 X 10' 1 m, I. 0 lbm = 4. 536 X 10* 1 kg, 1. 0 HP 








TABLE 6 - AMERICAN NON-RIGID AIRSHIP CHARACTERISTICS 



ORIGINAL PAGE IS 
OF POOR QUALTTYI 


TABLE 6 - (CONTINUED) 



26 



TABLE 7 - ZMC-Z CHARACTERISTICS (REFERENCE 7)* 


Length of Hull 149 ft. 5 in. 

Diameter of Hull (max.) 52 ft. 8 in. 

Fineness Ratio 2.83 

Displacement of Hull 202,200 cu. ft. 

Total Ballonet Displacement 50,600 cu. ft. 

Front Ballonet Displacement 22,600 cu. ft. 

Rear Ballonet Displacement 28,000 cu. ft. 

Ratio of Ballonet Volume to Hull Volume 25% 

Thickness of Skin 0.0095 in. 

Length of Car 24 ft. 

Width of Car 6 ft. 6 in. 

Number of Air Valves 3 

Number of Gas Valves 2 

Number of Fins 8 

Total Fin Area 44 0 sq. ft. 

Total Elevator Area 190 sq. ft. 

Total Rudder Area 95 sq. ft. 

Total Automatic Rudder Area 95 sq. ft. 

Engines (Wright Whirlwind J-5 2 

Power at 1,800 r.p.m 440 h.p. 

Propeller Diameter (all metal) 9 ft. 2 in. 

Lineal Feet of Seam 17,600 ft. 

Surface Area 19,436 sq. ft. 


PERFORMANCE DATA OF THE ZMC-2 METALCLAD 


Gross lift (100 per cent, inflation with 92 per cent, 
pure helium at 60 deg. Fahr. and 29.92 in. Hg.). 


Weight Empty 

Useful Load 

Crew (three) 600 lb. 

Fuel (200 gal.) 1,200 lb. 

Oil (25 gal.) 200 lb. 

Ballast (50 gal.) 420 lb. 

Passengers and Cargo 707 lb. 


Range with 250 gal. (Cruising Speed) 
Maximum Possible Range (still air) . 

Maximum Speed at 440 h.p 

Cruising Speed at 220 h.p 

Static Ceiling 


12,242 lb. 
9,115 lb. 
3,127 lb. 


760 mi. 
1,120 mi . 
70 m. p . h. 
56 m. p. h. 
9,000 ft. 


*1.0ft= 3.048xl0 m , 1.0 lbm = 4.536 X 10 ^ kg, 1.0 mi = 1.852 X 10^ m, 

1 . 0 mph = 4.470x 10 * m/s , lsqft = 0.0929 sqm, 1.0 cu ft = 2.832 X 10 ^ cu m 


27 - 



This minimum gage penalty disappears with increasing size. The Aircraft 
Development Corporation in the 1930's prepared proposed configurations for a 
variety of applications and compared notable rigid airships as illustrated in 
Table 8. The data of this table indicates the MC-72 metalclad compares 
favorably with the Akron. 

In Reference 9, C. P. Burgess compares the Aircraft Development Corp- 
oration's proposed MC-74* with the Akron. Burgess terms the MC-74 esti- 
mate "an honest and careful piece of work" but states in light of experience 
that he believes the actual empty weight would be about 15 percent over the 
estimate. This would bring the 209, 568 cu m (7,400, 000 cu ft) MC-74 to 
essentially 107, 049 . 6 kg (236, 000 lb). Burgess then shows that the reason 


TABLE 8 - COMPARISON OF AKRON (ZRS-4) AND 
PROPOSED MC-72 METALCLAD a 


ITEM 

COMPARA 1 : 
ZRS -4 b 

riVE DATA 
MC-7 2 

Displacement (Air), ft. 3 

7,250,000 

7,260,000 

100% Gas Volume, f t . ^ 

6,850,000 

7,080,000 

Total Lift, Helium Lifting .062 lb. /ft . / 



95% full, lb 

403,000 

417,000 

Weight Empty, lb 

233,000 

249,000 

Useful Load, lb 

170,000 

168,000 

Useful Load/Total Lift 

42.2 

40.3 

Useful Load per 1,000 ft.^ Displacement, lb. . 

23.5 

23.2 

Motors 

Maybach (8) 

Maybach (8) 


Horse-Power 

4,480 

4,480 

Maximum Speed, m.p.h 

84 

84 

Useful Load per Horse-Power, lb 

38.0 

37.5 

Number of Gas Cells 

12 

11 

Lift of Largest Cell, 95% full, lb 

57,000 

49,000 

Lift of Largest Cell/Useful Load 

33.5 

29.1 

Lift of Largest Cell/Total Lift 

14.1 

11.7 


a i.O ft = 3.048 X 10 1 m, 1.0 lbm = 4.536 X 10 1 kg, 1.0 HP = 7.457 X 10 2 watts 


1.0 mph = 4.470 X 10 ^ m/s, 1.0 cu ft = 2.832 X 10 2 cu m 

b Data from reference 7 which recognized the Akron data as 
unofficial. Akron data not changed from values of refer 
ence 7 since differences are not substantial. 


* 


The MC-74 (slightly larger than the MC-72) has the same air volume as 
Akron. 


- 28 - 



for the MC - 74 empty weight being le s s than the Akron (110, 147. 69 kg , or 
Z4Z, 830 lb, is the value Burgess uses) is not due to inherent advantages in 
the metalclad design. He states that they differ because of such items as 
lighter engines. In Table 9, Burgess compares the weight estimate of the 
Aircraft Development Corporation with his own relative to what is basically 
termed nonpropulsive structural weight. 

Burgess believes the comparisons favor the conventional rigid construc- 
tion by about 1416 kg (5000 lb) but the metalclad has a slight advantage in empty 
weight- to -gross lift ratio. In any event, Burgess 1 comparison supports the basic 


TABLE 9 - STRUCTURAL WEIGHT (POUNDS) OF 
AKRON AND MC-74 (REFERENCE 9)* 



AKRON 
(actual ) 

— 

MC-74 
(estimate ) 

MC-74 

(+15%) 

Hull plating or cover 

11,721 

42 , 032 

48,337 

Longitudinals 

22,641 

12,613 

14 , 505 

Main frames 

37,101 

27,548 

31,680 

Intermediate and splicing frames . . . 

12,067 

3,974 

4,570 

Corridors 

8,217 

5,485 

6,308 

Shear wiring 

5,200 

— 

— 

Gas cell wiring 

3,750 

— 

— 

Cover wiring 

1,905 

— 

— 

Miscellaneous structure 

2,820 

2,713 

3,120 

Total hull structure 

105,402 

94 ,3 65 

108,520 

Gas cells, valves, etc 

25,127 

19,239 

22,125 

Blower system 

— 

4 , 065 

4,675 

Total comparative weights 

130,529 

117,669 

135,320 

Comp, weight/gross lift 

32.4% 

27.4% 

31.6% 


*1 . 0 lbm = 4. 536 X 10" 1 kg 


- 29 - 








contention that the disadvantage that smaller metalclads have due to minimum 
gage considerations all but disappear when considering airships of the Akron 
and Macon size. * 

Although the ZMC-2 metalclad was used for 12 years, the airship never 
flew an extensive number of hours (about 2250 total). There are perhaps two 
reasons for this: 

1. Extreme unsteadiness in rough air due to exceedingly low 
slenderness ratio (in order to attain maximum structural 
efficiency) and the small size of the fins 

2. Available funds in the Navy were apparently being directed 
to the more conventional rigid LTA configurations rather 
than ’'experimenting 11 with new innovations. 

In a later article (see Reference 10), Burgess suggests altering the slen- 
derness ratio to attain a compromise between structural efficiency and aero- 
dynamic performance. In this same article, Burgess establishes the approx- 
imate weights and principal characteristics (see Table 10) of what he terms 
an ultimate airship (for 1939) that has the same air volume as the Akron and 
Macon. 

Burgess's suggestions relative to the nature of the ultimate airship in- 
clude: 

1. Using the metalclad construction with no compartment- 
alization. 

2. Using 15 percent ballonet volume. 

3. Reducing drag of the Akron and Macon by 30 percent by 
such approaches as placing the car in the nose of the air- 
ship and the air scoops for the ballonets in the nose area; 


Based on material properties of that point in time. 

25% ballonet volume is more typical for non-rigids, but Burgess suggests 
that during descent following an emergency ascension above pressure 
height that air be pumped directly into the helium with subsequent purifi- 
cation of the helium being required. This emergency provision also is 
normally available on non-rigid designs. 


-30 



31 


. 0 nauti mi = 1 . 85i X 1 0 m, 1.0 statute mi = 1.609 X 10 



using the metal hull for cooling the helium, which in turn 
is used to cool the radiators and water recovery apparatus. 

4. Some minor improvements in specific fuel consumption 
and propeller efficiency that have since been realized. 

Since the Burgess configuration has an empty weight of about 60 percent 
that of the Akron (which has the same total displacement) and a 75 percent 
greater useful load capacity, the configuration should be considered in the 
conventional LTA parametric weight studies. 

Burgess was clearly impressed with the potential of the metalclad airship 
but expressed concern relative to manufacturing costs of the larger metalclads. 
Estimates by the Aircraft Development Corporation during the 1930's (Refer- 
ence 7), however, do not indicate excessive manufacturing costs. 

In Reference 11, Adm. Rosendahl states that flying the ZMC-2 was a "very 
tricky" proposition due to sudden changes in buoyancy resulting from the rapid 
transmission of heat to and from the helium by the metal hull, which was in 
direct contact with the helium. Other considerations tend to moderate the 
thinking that the metalclad is a concept without fault or shortcoming; these 
considerations are discussed in the parametric analysis subsection of this 
report. This is not to say that there are not viable solutions for those prob- 
lems of which we are aware or for those problems that are unknown. With 
the metalclad, however, all aspects of its design, manufacture, and operation 
must be carefully considered. 

Table 11 gives a detailed weight breakdown for the ZPG-3 W as configured 
for its aircraft early warning (AEW) military mission and with its military 
equipment stripped. 


Semi-rigid Airships 

Table 12 summarizes the characteristics of the German semi-rigid air- 
ships. As in the rigids, a general evolution to larger, faster, and at the same 
time more efficient configurations can be seen in this table. 


- 32 - 



TABLE 11 - DETAILED WEIGHTS FOR ZPG-3W WITH AND 
WITHOUT MILITARY EQUIPMENT (REFERENCE 13)* 


Item 

Weight (pounds) 

Weight empty (total) 

67, 566 + (56, 58Z ) * 

Envelope group (dacron): 

41, 986 (41, 986) 

Enve lope 

12, 690 

Ballonets 

Z, 2 1 1 

Ai r lines 

514 

Car suspension 

1, 414 

Bow stiffening and mooring 

1 , 559 

Fin suspension 

377 

Car fairing 

4 84 

Access shaft and walkway 

44 1 

Mi scellane ous 

2, 296 

Tail group 

3,701 (3, 701) 

Car group 

4,570 (4,570) 

Alighting gear group 

1,190 (1, 190) 

Pressure group 

2,076 (2,076) 

Ballast group 

750 (750) 

Surface control group 

1,230 (1,230) 

Outrigger group 

880 (880) 

Engine section and nacelle group 

1,446 (1,446) 

Propulsion group: 

8,307 (8,307) 

Engine installation 

3, 527 

Accessory gear boxes and drives 

207 

Air induction system 

34 

Exhaust system 

135 

Cooling system 

322 

Lubricating system 

484 

Fuel system 

2, 160 

Engine controls 

106 

Starting system 

75 

Propeller installation 

1, 527 

Auxiliary power unit 

760 (0) 

Instruments and navigation equipment group: 

580 (580) 

Instruments 

486 

Navigational equipment 

94 

Hydraulic group 

430 (430) 

Electrical group 

3,176 (794) 

Electronics group 

12, 162 (4, 320) 

Furnishings and equipment group 

2, 164 (2, 164) 

Air conditioning and anti-icing group; 


Equipment group 

1,363 (1,363) 

Air conditioning 

1 , 307 

Anti -icing 

56 

Auxiliary gear 

795 (795) 


^ Numbers without parenthesis refer to the ZPG-3W as configured for military mission. 
♦Numbers with parenthesis refer to the ZPG-3W without military equipment. 

*1.0 lbm = 4. 536 X 1 O' 1 kg 


ORIGINAL PAGE IS 
OF POOR QUALITY! 


33 


TABLE 12 - CHARACTERISTICS OF GERMAN SEMI-RIGID AIRSHIPS (REFERENCE 1)* 




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Table 13 summarizes the characteristics of two notable Italian configura- 
tions, the Roma and the Norge, as well as the American RS-1. The historic 
flight from Rome to the North Pole in 1926 by the Norge is reported in Refer- 
ence 12. Appendix A of Volume IV summarizes the characteristics of other 
Italian semi-rigid configurations . 

Analysis of Data (Rigid, Non-rigid, Semi-rigid) 

The rigid airship data from Tables 1, 3, and 4 have been plotted in Figure 
6 in the form of useful lift-to -gros s lift ratio as a function of air volume. 
Figure 6 also shows the same ratio for the airship that Burgess in Reference 
3 refers to as the ultimate airship, as well as the 1944 Goodyear design for a 
290, 280 cu m (10, 250, 000 cu ft) rigid 

Several factors are apparent from Figure 6: 

1. The British R-100 and 101 do not compare favorably with 
the other configurations, which is why they are often re- 
ported as being overweight. 


1- R‘34 6. GRAF ZEPPELIN 11. HINDENBURG 



* SAME AS AIR V0LUMF. CUBIC FEET x 10 

AIRSHIP TOTAL VOLUME- CUBIC FT X 10’ 6 

Figure 6 - Useful Lift -to -Gros s Lift Ratio vs Airship Volume 
(Past Rigid Airship Configurations) 

- 35 - 




TABLE 13 - CHARACTERISTICS OF RS-1, ROMA, AND NORGE SEMI-RIGID AIRSHIPS 

(REFERENCE 3)* + 



36 




2. German military rigids at the end of World War 1 exhibited 
much higher useful lift-to -gross lift ratios than any air- 
ships that followed. 

3. The significant technology advancements incorporated in 
the Akron, Macon, and Hindenburg rigids are not apparent 
because the hulls of these configurations were noticeably 
stronger (and accordingly heavier) than prior designs. 

The necessity for the added strength resulted from flight 
experience with the earlier rigids and the wind tunnel 
testing associated with these most recent airships. The 
relative hull strengths of the more notable rigid airships 
are provided in a subsequent subsection of this overview. 

4. Hydrogen-filled airships have a superior useful lift-to - 
gross lift ratio than helium -filled airships. 

5. While the two lines portraying the "average” useful lift- 
to -gross lift ratios for hydrogen- and helium -filled air- 
ships are not exact, they generally illustrate: 

a. Hydrogen filled airships generally have exhibited 
useful lift-to -gros s lift ratios ranging from 0.45 to 
0.5 0. 

b. Helium -filled airships generally have exhibited a 
useful lift -to -gros s lift ratio of about 0.40. 

The ratio of these values is slightly greater than the ratio 
of the lift of the gases although not significantly so. 

6. The proposed 1944 Goodyear design has a useful lift-to- 
gross lift ratio comparable to prior experience but is 
somewhat improved in view of interim technology advances. 

The column entitled "Percent of Total" in Table 4 basically 
shows the areas of the design in which these improvements 
took place. 

7. The improvement associated with C. P. Burgess ultimate 
airship is readily apparent. 

The empty weight -to -gas volume ratio better attests to the efficiency of a 
given past configuration than the useful lift-to -gros s lift ratio. This volume 


37 - 



ratio measures efficiency in that it considers the total "cost" to achieve a lift - 
ing capability (empty weight) as well as measures the total lifting capability 
achieved (the gas volume). This parameter also removes the effect of the dif- 
ferences in lifting gases and conditions of comparison (percent inflation, purity 
of lifting gas, and temperature of lifting gas). It also is one of the better 
methods to compare past rigid, non-rigid, and semi-rigid configurations. It 
is, however, somewhat unfair to the recent non-rigid configurations in that it 
does not account for the benefits derived by heavy takoffs but does account for 
the penalty paid in terms of the increased landing gear weight required to per- 
form a heavy takeoff, since the gear increases the empty weight. The lower 
the empty weight -to -total gas volume ratio the more efficient is the configura- 
tion. 

In Figure 7, the empty weight-to -gas volume ratio is a function of airship 
gas volume for the rigid airships of Figure 6. Some of the same conclusions 
in Figure 6 are still discernible but generally speaking the hydrogen- and 
helium -filled airships are very comparable in Figure 7. 


0.05 

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R. 34 9. HINOENBURG 

R-38 10 . MOST EFFICIENT GERMAN AIRSHIPS 

SHENANDOAH OF MW I 

LOS ANGELES 11. ULTIMATE AIRSHIP BY C.P. BURGESS 
GRAF ZEPPELIN (1937) 

R-100 1? IQdd r.nnnvrflD nrctnw 


3 

□ 

D 


. q5 

7 

8 

R- 101 

AKRON & MAC 

ON 

O 



8 

— 




8 

1 


12 

□ 

c 

>10 





11 

n 




LEGENE 

): 

O HYDROGEN 
□ HELIUM 



NOTES: OAT 
1 . 0 
1 n 

FROM TABLE 
ft - 3.041 
i 1 bm = 4.5; 

i x 1 0” 1 m ; 
36 x 10~ ] k 


zn 

O 

UJ 

3 

>- 

)— 

Q. 

3E 






— — l . u 

g 


5 6 7 8 , 

AIRSHIP MAXIMUM GAS VOLUME - CUBIC FT X 10 " 6 


Figure 7 - Empty Weight-to-Gas Volume Ratio as a Function of Gas Volume 

(Past Rigid Airship Configurations) 


-38 




These data reflect different design criteria such as design velocities. 

Note, however, that the hull strength of the Akron, Macon, and Hindenburg 
is very similar {see Page 110). 

The non-rigid and semi-rigid data from Tables 5, 6, 12, and 13 have been 
plotted in Figure 8 in the form of useful lift-to-gross lift ratio as a function of 
total volume. Figure 8 shows the following: 

1. Early German non-rigid configurations exhibited a greater 
useful lift-to-gross lift ratio than subsequent configurations 
for essentially the same reasons cited for the early German 
rigids . 

2. The improvement within the helium -filled non-rigid air- 
ships is technology related and not size related. As in 
the rigid airships, the technology impact is not readily 
apparent due to corresponding increases in strength 
criteria. In addition, the increase in design velocity 
(which converts to a factor of four in terms of dynamic 


1. MOST EFFICIENT GERMAN MILITARY NON-RIGID (1917) 

2. EARLY AMERICAN NON-RIGID - B TYPE (1916) 

3. RECENT AMERICAN NON-RIGID - ZPG-3W (1969) 

4. MOST EFFICIENT GERMAN MILITARY SEMI-RIGID (1914) 

5. ROMA SEMI-RIGID (1919) 

6. NORGE SEMI-RIGID (1923) 

7. RS-1 SEMI-RIGID (1925) 

8. GOODYEAR NON-RIGID DESIGN STUDY 



AIRSHIP TOTAL VOLUME - CUBIC FEET X 10" 3 

* STATIC EXCEPT AS NOTED 


Figure 8 - Useful Lift*-to-Gross Lift Ratio versus Airship Volume 
(Past Non-rigid and Semi-rigid Configurations) 


39 




pressure for doubling the design velocity) between the ZPG-3W 
and the 1919B nonrigid tends to prevent improvement recognition. 

3. The semi-rigid airships do not appear significantly differ- 
ent in terms of the parameter plotted than the non-rigids 
for a similar period in time. 

4. The benefit of dynamic lift has been included in Figure 8 
with respect to the ZPG-3 W and the ZPW-1 design study 
configuration. 

Figure 9 represents a comparison between past rigids, non-rigids, and 
semi-rigids. The parameter used for the comparison is empty weight-to- 
maximum gas volume ratio. The following comments are offered relative 
to Figure 9: 


0.05 


0.04 


10.03 


i 0. 02 


* 0.01 


SEMI-RIGIDS 



5. A 

o — 


, MOST RECENT RIGIDS (GERMAN & AMERICAN) 

Jb B 


EFFECT OF HEAVY TAKE-OFF 


2 

O 


□ 

6 


LEGEND: 

O HYDROGEN 
□ HELIUM 


1 . 

2 . 

3. 

4. 

5. 

6 . 

7. 

I — 8. 

9 . 

10 . 

11 . 

12 . 


MOST EFFICIENT GERMAN MILITARY NON-RIGID (1917) 

MOST EFFICIENT GERMAN MILITARY RIGID (1917) 

MOST EFFICIENT GERMAN MILITARY SEMI-RIGID (1914) 

ITALIAN SEMI-RIGIDS (4. A -ROMA AND 4.B NORGE, 1919 & 1923 RESPECTIVELY) 

MOST RECENT GERMAN RIGIDS (5. A -GRAF ZEPPELIN AND 5.B HINDENBURG, 1928 & 1936 RESPECTIVELY 
MOST RECENT AMERICAN RIGIDS (AKRON & MACON, 1931 AND 1933 RESPECTIVELY 
MOST RECENT AMERICAN NON-RIGID (ZPG-3W, 1959) 

GOODYEAR ZWG-1 NON-RIGID DESIGN STUDY 

NON-RIGID K-SHIPS (1931-1945) 

NON-RIGID G-SHIPS (1935) NOTES : 1.0 ft - 3.048 x 1 0'" 


EARLY AMERICAN NON-RIGIDS (C TYPE 1918) 
AMERICAN SEMI-RIGID (RS-1, 1925) 


1 .0 Ibm = 4.536 


10 - 


rn, 

1 kg 


10 


AIRSHIP MAXIMUM GAS VOLUME - CUBIC FT X 10 


-6 


Figure 9 - Comparison of Past Rigid, Non-rigid, and 
Semi-rigid Airship Configurations 


-40 




1 . 


Semi-rigids and non-rigids for a comparable period in time 
(1916 to 19^5) do not appear to differ significantly in terms 
of efficiency*, based on comparing data points 3, 4. A, 4.B, 

11, and 12. In general, the design criteria, velocity, and mate- 
rials were comparable in these designs and the sizes were 
similar . 

Z. The most recent rigids (data points 5. A, 5.B, and 6) have 

relatively the same efficiency. All these configurations have 
essentially the same design velocity and were of similar sizes. 
The Akron, Macon, and Hindenburg used a more severe hull 
strength criteria than the Graf Zeppelin. However, this was 
offset by the Akron, Macon, and Hindenburg using improved 
materials and the Hindenburg using an improved powerplant. 

3. The ability of the non-rigid designs to perform heavy takeoffs 
has been translated to an increase in efficiency; this has been 
done by converting the dynamic lift into an effective increase 
in gas volume using a lift value for helium of 0.993 kg/cu m 
(0.06Z lb/cu ft). Volume II assesses the "real gain 11 in 
efficiency resulting from heavy takeoffs.** 

4. An increase in efficiency in the rigid design over certain 
size ranges also can be realized by heavy takeoff as discussed 
in Volume II. 

5. The rigids and non-rigids of data points 5. A, 5.B, 6, 9, 
and 10 from a comparable period in time (1928 to 1936) 
indicate that the rigid configuration is historically some- 
what between 12 and 25 percent more efficient than 


* 

Meaningful comparisons cannot be made over large periods in time general- 
ly due to changes in strength criteria based on experience and wind tunnel 
testing, technological improvements, and general trend to higher-speed 
designs as time passed. 

** # 

This is accomplished by defining the relative gain in useful lift versus the 
relative increase in empty weight due to increased landing gear weight. 


- 41 - 


the non-rigid.* Again, the reader must refer to Volume II 
to compare the two configurations precisely. 

6. A comparison between the ZPG-3W and the rigid airships 
of the 1930 era is probably meaningless. 

Figure 10 shows the effect that altitude has on useful lift. It can be seen 
from Figure 10 why airships have historically been considered relatively low- 
altitude vehicles. It is reasonable to suggest on the basis of the plot that, as a 
rule, commercial operations with a modern airship vehicle (MAV) should be 
limited to about 15Z4 m (5000 ft) above sea level to maximize productivity. 
Inherent in that statement is the general conclusion that commercial operations 
would not be suited to routes passing over mountainous terrain. 

Use of the airship in military applications requiring high-altitude capability 
is not nearly such a significant concern. The “penalty 11 paid to attain an opera- 
tional capability of 6096 m (20, 000 ft) can quickly be offset in a high-priority 
military need situation when it is realized the airship may be the only viable 
approach for meeting the need. 



Figure 10 - Altitude versus Useful Lift 


This conclusion does not suggest that rigids are categorically preferable over 
non-rigids since such a determination involves many factors. In addition, as 
shown in Volume II, the efficiency gain indicated in the rigids is principally 
due to their larger size. 


- 42 - 









Figure 11 shows the relationship between structural weight and volume of 
past rigid airships. The data of the figure is for airships that used different 
aerodynamic loading criteria, used different load factors and factors of safety, 
considered military versus commercial criteria in their design, exhibited dif- 
ferent maximum speeds, and used different component material strength-to- 
weight ratios. 

Thus, while the data have been interpreted linearly to facilitate an ap- 
praisal of the data trend, the relationship between wieght and volume is not 
necessarily linear for a given set of the above considerations. The parame- 
tric analysis subsection of this report illustrates the actual trend that exists 
between weight and volume for given sets of variables. 

Figure 12 presents one figure of merit (FOM) of interest and shows pay- 
load ton-miles per hour as a function of gross weight for various notable 
rigid airships of the past. The British rigid data have not been plotted since 
they do not fit the trends shown because of the structured rather excessive 
weight. Payload is defined as useful load minus fuel load required to traverse 

240 
220 
200 

180 
160 
° 140 

X 

£ 120 
z 
=3 

° 100 
I 

80 
z 
o 

UJ 

3 60 
40 
20 
0 

0 

Figure 11 - Rigid Structural Weight versus Airship Air Volume 



- 43 - 


TOTAL STRUCTURE WEIGHT 



Note: 1.0 ton = 9.072 x 10 2 kg, 

1 . 0 STATUTE MILE = 1.609 x 1 0 3 
1.0 1 bm = 4.536 x 10"^ kg 



□ <J 

z •— < 
>— cc 
u: • — 


STATUTE NILES 


AIRSHIP GROSS WEIGHT X 10' J LB 


Figure 12 - Payload Ton-Miles per Hour versus Gross Weight (Rigids) 


the range indicated at a velocity of 5 0 knots in a zero headwind condition. The 
curves provide a base so productivity can be compared with past rigids and 
those emerging from the parametric study. The results cannot be used to 
compare data available on other forms of transportation unless similar ground 
rules are adopted to define the relation between useful lift, payload, and fuel 
load. Fifty knots was not necessarily the optimal speed in terms of the FOM 
plotted but was a velocity at which data were available for all configurations. 
There is a variety of design criteria represented; accordingly, the linearized 
interpretations are not necessarily representative. 

Figure 13 presents the FOM of payload ton-miles/(hours ) (empty weight) 
as a function of gross weight for past rigids. The definitions in Figure 12 
also apply to Figure 13, with generally the same qualifications applying. The 
parametric data are compared with these data in the parametric study. 

The ZPG-3W non-rigid airship data point is included so that the parame- 
tric results of Volume II can be compared. Any specific comparisons 


- 44 - 






Note: 


1 .0 ton - 9. 072 x }0 2 kg, 

1.0 STATUTE MILE - 1.609 * 1 0 3 m , 
1.0 lbfn » 4.536 x 1 0- 1 kg 



Figure 13 - Payload Ton-Mile s/(Hours )(Empty Weight) 
versus Gross Weight (Rigids) 

between the ZPG-3W and the remainder of the data of Figures 12 and 13 are 
for the most part meaningless due to differing specifications to which the air- 
ships were built. 

HISTORICAL MARKETS, MISSION COSTS, AND 
OPERATING PROCEDURES 

General 

The historical missions and markets have been broadly grouped as com- 
merical and military. The following military and commercial operations are 
discussed in this subsection: 

1. German military missions during World War I (rigid air- 
ship operation) 

2. Seasonal pleasure flying in Germany between 1910 and 
1914 (rigid airship operation) 


- 45 - 




3. Scheduled commercial service between Friedrichshafen, 

Germany, and Berlin during 1919 (rigid airship operation) 

4. Scheduled seasonal service between Friedrichshafen and 
South America between 1932 and 1937 (rigid airship oper- 
ation) 

5. Scheduled seasonal service between Friedrichshafen and 
Lakehurst, N. J. , between 1936 and 1937 (rigid airship 
ope ration ) 

6. American military missions since 1916 (rigid and non- 
rigid airship operation) 

Operations and Economics 
German Military Activities 

At the outset of World War I, the German military had a fleet of approxi- 
mately 12 Parseval and Siemens -Schuret non-rigid airships. These airships 
had little practical use during the war because of their limited size and speed. 
The commercial rigid airships of the Zeppelin Delag fleet were immediately 
pressed into service; thus, commercial services were suspended. 

Zeppelin-type rigids totaled nine at the outset of hostilities. Ultimately, 

88 airships were built by the Zeppelin Company for the German war effort. 

The Schutte - Lanz Company provided an additional 18 rigids. These airships 
were ultimately abandoned, however, in favor of the Zeppelin type because 
moisture caused the wooden structural members of the Schutte-Lanz airships 
to deteriorate . 

Bombing by airship started in earnest during the siege of Antwerp, Bel- 
gium, with bombs improvised from artillery shells. The Zeppelins were 
employed extensively on the Russian front until that front collapsed. Raids 
on London started in 1915 and grew in intensity through 1916. 

In some cases, fleets of as many as 16 airships were used. Table 14 
summarizes pertinent characteristics of selected bombing missions. Later 


- 46 - 



TABLE 14 - SELECTED WORLD WAR I GERMAN BOMBING RAIDS 





raids were carried out at altitudes in excess of 6400. 8 m (21, 000 ft) and bomb 
loads were in excess of 5443.2 kg (12, 000 lb). The bombing raids became 
reasonably effective, with many large munition factories disabled for extended 
periods (Reference 14). The raids began to decrease in 1917 when the alti- 
tude capability and incendiary ammunition of the airplanes improved. 

After 284 raids, of which 188 were considered successful under Army 
operation, the Zeppelins were transferred to naval service in the North Sea. 
These airships played an important scouting role in the famous battle of Jut- 
land, the only large-scale naval battle of World War I. Reportedly, without 
the Zeppelins in this battle, the German fleet would have been eliminated. 

The Zeppelins were used in a wide variety of ways by the Germany Navy. 
Forty Zeppelins in the latter stages of the war broke up extensive mine fields, 
stopped enemy merchant ships at sea, and bombed out enemy locks and dry- 
docks . 

During World War I, German Army and Navy airships flew approximately 
26 000 hours , or nearly 2.315 X 10^ m (1,250,000 m), during approximately 
5000 flights. About 51 airships were lost (References 15 and 16): 

1. 17 downed by incendiary projectiles from artillery or 
airplanes 

2. 19 heavily damaged by artillary 

3. 7 stranded in enemy territory 

4. 8 destroyed in hangars by enemy action 

At the end of the war, Germany resumed commercial passenger and 
freight services with the airship, a service abandoned in 1914 so that all ef- 
forts could be focused on providing airships to the military. 

German Commercial Activities 

Between 1910 and 1937, German Zeppelins were used for four different 
sustained commercial operations. 


- 48 - 



TABLE 15 - LUFTSCHIFFBAU ZEPPELIN COMMERCIAL SERVICE (1910 TO 1937) 



Data from transmittals from officers of Luftschiffbau Zeppelin to officers of Goodyear Zeppelin 

















TABLE 15 - (CONTINUED) 



50 


rejected maximum utilization rate - (365) 


Seasonal Pleasure - The initial service operated by the Deutsche 
Luftschiffahrts-Aktien-Gesellschaft {Delag), which was a subsidiary of the 
Luftschiffbau Zeppelin (L-Z) Company, operated sightseeing and intercity 
trips during 1910. Available data from the 1910 service is given in Table 15, 
along with data pertinent to the entire German commercial service. 

Figure 14 shows the utilization rate for the entire L-Z commercial his- 
tory ( 1 9 1 0 to 1937). The airship in the L-Z service was seasonal and within 
a season may have been periodic due to weather, especially from 1910 to 
1914. If a modern commercial airship would not be subject to any significant 
schedule alteration as a result of seasonal effects (if it were, it never would 



Figure 14 - Utilization Rate as a Function of Stage Length for German 

Commercial Service (1910 to 1937) 


- 51 - 




exist other than as a novelty), the demonstrated utilization can be modified 
by factoring out seasonal and periodic interruptions of the past rigids; this 
has been done in the cure labeled "projected maximum." The projected max- 
imum utilization rate in hours per day is calculated as follows: 

. , . / number of actual hours flown in year \ 

' ^number of days actually flown per year) 

The value of this parameter is included in Table 15 for each airship of the 
commercial L-Z service. 

The ratio of the average block velocity-to-airship maximum velocity ratio, 
plotted in Figure 15, also can be obtained from Table 15. This curve accounts 
for the effects of head wind, tail wind, weather avoidance maneuvers, and 
holding pattern for better landing conditions. The same ratio also has been 
presented for modern-day commercial passenger jets and passenger heli- 
copters . 


1910-1914 SERV 
GRAF 

(•/ ZEPPELIN . J 

\ (1930) Xcr 0 

ICE 

o 

— 
^ GRAF 

\v^EP 

^ 

T 

PELIN 193- 

r GRAF ZEPP 
\ (1935) 

TIN HIND 
BURG 
193, 

EN- 

\ 

- — 








3 \ / 

^ LZ-120 


- MODER 



rv 

N DAY PASS 

L. 

-GRAF ZEPPELIN 
ENGER JET (BASED ON H 

OP LENGTH) 
AVIATION W 

- REFERE 
EEK, 3-31- 

NCE 

1975 

- V- MODEf 
REFEf 

3N DAY PASS 
3ENCE AVIAT 

1 l 

ENGER HELICOPTER 
ION WEEK MARCH 31 , 1 

975 











. . - . .. _j 



NOTES 

C 

1 

lata from 
.0 STATU' 

i 

Table 15 
re MILE = 



1.609 x 


10 3 m 
1 

DATA 

FROM TABLE 



15 



. 

o 

o 


o 

2 


STAGE LENGTH -STATUTE MILES X 10 


-2 


Figure 15 - Average Block Velocity Maximum Velocity Ratio 


52 - 




Similar sightseeing and intercity flights were conducted in 1911 with LZ -8 
and LZ - 1 0 airships. The LZ-11, LZ-13, and LZ-17 were operated until the 
outbreak of World War I, at which time the Delag ships were placed into mili- 
tary service. Reference 8 reports that the total operating costs between ZZ 
June 1910 and 31 July 1914 for the Delag operations were 4, Z60 ,000 reich 
marks ($1, 700, 000 at an exchange rate of RM 1. 00 = $0.40); this reportedly 
covered 47. 7 percent of the expenditure, with the balance apparently more 
than covered by the German government. In return, the naval and other mili- 
tary crews were trained during the commercial flights, and the airships were 
required to meet certain limited military requirements. 

Scheduled Commercial Service (Germany) - The commercial service was 
resumed after the war with the Bodensee (LZ-1Z0), which flew between Fried- 
richshafen and Berlin from Z4 August 1919 to 1 December 1919, with an inter- 
mediate stop at Munich during part of the service. The service reportedly 
operated at a los s despite a load factor of 100 percent on essentially all flights. * 
The service was extremely popular as evidenced by the load factor; according- 
ly, L-Z planned to introduce additional ships with flights beyond the German 
borders. The Bodensee was lengthened in December 1919 so that the passen- 
ger load could be increased from ZZ to 3 0; undoubtedly, this was undertaken 
to resolve the reported loss situation. The Nordstern (LZ-1Z1) was build be- 
tween October and December of 1919 and had characteristics essentially iden- 
tical to the lengthened Bodensee. With these two ships carrying 30 passengers 
each, it was intended to open an airship line in the spring of 19Z0 between 
Switzerland and Stockholm by way of Berlin and to Italy and Spain. The Inter - 
Allied command forbade further commercial operations, and the Bodensee was 
turned over to Italy and the Nordstern to France. 

Scheduled Commercial Service (South America) - Commercial operations 
were resumed by L-Z in 19Z8 with the Graf Zeppelin. Table 16 summarizes 
readily available data on the Graf Zeppelin. Operations with the Graf were 
suspended shortly after the loss of the Hindenburg on 6 May 1937 since helium 

- _ 1 
The Bodensee (approximately 198, Z40 cu m (700, 000 cu ft) was the largest 
airship that the Inter-Allied Command would permit Germany to build. 

This factor, coupled with the severe inflation of that time, no doubt con- 
tributed to and was possibly responsible for the reported loss. 


- 53 - 


TABLE 16 - DATA RELATIVE TO GRAF ZEPPELIN TRANSOCEANIC 
FLIGHTS AND PASSENGER LOAD FACTORS 

I. TRANSOCEANIC CROSSING HISTORY 


Year 

So . 
Pass . 

Atlantic 

Mail 

No. Atlantic 

Pacific 

Total 

1928-9 



5 

1 

6 

1930 

1 


1 


2 

1931 

6 




6 

1932 

18 




18 

1933 

17 


1 


18 

1934 

24 




24 

1935 

32 

* 6 



38 

1936 

24 


2 


26 

1937 

6 




6 

TOTAL 

128 

6 

9 

1 

144 


♦These 6 crossings represent regular scheduled mail crossings from 
Pernambuco to Africa and return without landing in Africa. The 
mail was dropped by parachute and taken aboard with a line. Three 
such round trips were made, yielding 6 crossings. Naturally no 
passengers were carried. 


SOUTH 

AMERICAN SERVICE 

LOAD FACTORS (1932- 

-1935) 


Year 

Crossings 

Passengers 

Pass/Flight 

% Capacity 

1932 

18 

185 

10.3 

51.5 

1933 

17 

215 

12.6 

63.0 



*212 

12.5 

62.5 

1934 

24 

429 

17.9 

89.5 



*401 

16.7 

83.5 

1935 

32 

572 

17.9 

89.5 



*568 

17.7 

89.0 


♦On a few flights during 1933, 1934, and 1935 all passenger accommo- 
dations were sold out and additional passengers were accomodated 
in the keel of the ship. The figures designated with ♦ give the 
number of passengers after deducting the number of passengers carried 
in the keel. In all cases 100% capacity has been taken as 20. 

Three round trips to South America were made in 1931 before estab- 
lishing the service which was first scheduled in 1932. 

In 1935, several mail flights were also made across the So. Atlantic, 
but as these flights were purely for mail carrying and no passengers 
were carried, they have not been entered here. 

A crossing may be designated as a transoceanic flight, either Fried- 
richenafen to Pernambuco, Seville to Pernambuco, or the reverse. 


54 



was unavailable to Germany and the Hindenburg experience had made commer- 
cial airship operation without it difficult to promote. The LZ-130 (Graf Zep- 
pelin II), which first flew on 14 September 1938, was intended to be a strictly 
commercial ship, but was never used in that capacity because an agreement 
for the United States to provide helium could not be reached. 

Among its accomplishments, the Graf Zeppelin traveled around the world 
in an elapsed time of 20 days, 4 hours, and 14 minutes. It covered 3.419 X 10 m 
(21, 249 mi) in a flying time of 300 hours and 20 minutes, an average of nearly 
31. 74 m/s (71 mph ) . The four nonstop stage s of the trip were as follows: 

1. August 15 to 19, 1929 - Friedrichshafen to Tokyo, nonstop, 

7 

1.028 X 10 m(6386 mi) in 101 hours and 49 minutes, over 

Berlin, Stettin, Danzig, Estonia, Wologda (Russia), Yakutsk, 
and Siberia. A crew of 40 plus 20 passengers. 

2. August 23 to August 26, 1929 - after refueling and gasing, 

Tokyo to Los Angeles, nonstop, 9.651 X 10 m (5998 mi) 

in 79 hours and 3 minutes. A crew of 41 plus 18 passengers. 

3. August 27 to August 29, 1929 - Los Angeles to Lakehurst, 

nonstop, 4.821 X 10^ m (2996 mi) in 5 1 hours and 57 minutes, 
via El Paso, Kansas City, Chicago, Detroit, and New York. 

A crew of 34 plus 16 passengers. 

4. September 1 to 4, 1929 - Lakehurst to Friedrichshafen, 
last nonstop stage, 8.475 X 10^ m (5267 mi) in 67 hours 
and 31 minutes, via Azores, Santander, and Bordeaux. A 
crew of 40 plus 22 passengers. 

The engine was refueled at Tokyo, Los Angeles, and Lakehurst. Only 
plugs and several valves were changed on the entire trip. Passengers included 
noted men and women and journalists from various countries flying one or 
more or all stages. U. S. naval officers made the trip from Lakehurst. 

The transoceanic crossing of the Graf Zeppelin for its entire period of 
service along with the load factors attained on the South Atlantic service from 
1928 through 1935 are summarized in Table 16. 

The fare schedule for the 1936 season is present in Figure 16. Reference 
8 reports that the 1932 service required a total expenditure of $19, 500 per 


- 55 - 



NORTH ATLANTIC SERVICE 

Fronkfurt a /Main, Germany, to Lakehurst, N. J. 
Laktkurtf, N. J., to Frankfurt a/Main, Germany. 


For the season of 1936 ten round-trips of the L. Z. 129 are 
scheduled between Frankfurt a/Main and Lakehurst, N. J. 
beginning in May and lasting through to the middle of October. 


Duration of the westbound voyage will be about three days and 
for the eastbound voyage two and one-half days. See separate 
sailing schedule for tentative dates. 


RATES 

(Subject to Change) OncWay 

LAKEHURST— FRANKFURT OR FRANKFU RT— LAKEHURST * 40 o* 

(2 IN A ROOM BASIS) 

SOLE OCCUPANCY. DOUBLE ROOM 680 

The rates to and from Seville, if a landtnq is made there, will be $40 less in either direction. 
*The rate for the first voyage from Frankfurt to Lakehurst will be $100 additional. 


Round T rip 
$ 720 



EUROPE— SOUTH 

AMERICA SERVICE 



This service has been in operation durinq the past four years 

to Pernambuco is three days, 

to Rio de Janeiro 

4 days. Regular 

and is in operation again this year by the GRAF ZEPPELIN, 
with fortnightly departures in each direction. The time Frankfurt 

fortnightly service from Apri 

1st to December 


RATES 



(Subject to Change) 

Two in Room 

Room 



per Berth 

Alone 

FRANKFURT— PERNAMBUCO 


R.M. 1400 

R.M. 2100 

FRANKFURT— RIO DE JANEIRO 


1500 

2200 

FRANKFURT— SEVILLE 


400 


SEVILLE— PERNAMBUCO 


1300 

2000 

SEVILLE— RIO DE JANEIRO 


1400 

2100 


Figure 16 - Fare Schedule for Graf Zeppelin 
and Hindenburg (1936$) 


trip (1932$), which appears reasonable on the basis of the Hindenburg's 1936 per- 
trip expenses. Using the 1936 fare schedule (which does not appear significantly 
different from the 1932 rates) and the load factor information from Table 16, 


-56 - 




the passenger revenue (in 1932$) per trip in 1932 averaged $4820 (all 
passages round trip, Seville to Pernambuco and return, double occupancy). 

The maximum average revenue (in 1932$) would have been $9064 (all one- 
way passages, Frankfurt to Rio, single occupancy). Reference 8 reports 
the mail revenue (in 1932$) at $1 1, 330 per trip for 1932. Freight revenue 
was small as was the amount of freight carried per trip. From this, then, 
the minimum average revenue (in 1932$) per trip was $16, 120 and the maxi- 
mum average revenue (in 1932$) was $20, 394. This would indicate that the 
first year’s expenses were probably not covered by mail and passenger revenue. 

Scheduled Commercial Service (North Atlantic) - The Hindenburg was used 
on the North Atlantic route due to the fact that its cruise speed was higher than 
the Graf Zepplin. Operating costs for the North Atlantic flights of the Hinden- 
burg for 1936 are determined below from the performance data of Tables 17 and 
18. The operating costs of the Hindenburg during 1936 over the North Atlantic 
route are given below: 

1. Total annual expense (1936$) 


a. 

Twelve and one -half percent 
amortization of ship ($2, 300, 000) 

0287 , 500 

b. 

Twenty percent amortization of 
five engines (four on ship, one 

0 60, 000 


spare ) 

c. 

Overhaul, alterations, new parts, 
maintenance, and repairs (includ- 
ing amortization of tools and 



equipment ) 

0120 , 000 


Reich mark = $0.40 (1932). 

** i 

The extent of a subsidy, if any, is not known. 

Data contained in this analysis transmitted in personnel correspondence 
of officers of Luftschiffbau Zeppelin to officers of Goodyear Zeppelin. 


- 57 - 



Insurance 


d. 


e. 


All risk on ship (five 
percent) 

Crew accident 

Third-party liability 

Engine breakdown 

Crew baggage 


$130, 000 
$ 11,600 
$ 2, 000 
$ 5,600 

$ 250 


Crew's wages (three flight watches 
and reserves ) 


f. Administrative, engineering, and 
selling overhead applicable to 
the airship 


Total fixed charges (1936$) 


$149, 450 

$ 110 , 000 

$ 45, 000 
$771, 950 


TABLE 17 - SUMMARY OF HINDENBURG'S 1936 NORTH ATLANTIC 
SERVICE (WESTWARD CROSSINGS) * 


Flight 

No. 

Date of 
Departure 

Flight 

Time 

Distance 
Nau. Miles 

Passengers 

Crew 

Mail 

Kg 

Freight 

Kg 

Fuel Oil 
Kg 

Lub. Oil 
Kg 

1 

May 6 

61:40 

3880 

50 

55 

1059 

134 

50,350 

4,000 

2 

May 16 

78:50 

3920 

40 

54 

135 

26 

54,160 

3,400 

3 

June 19 

61:20 

3692 

43 

54 

156 

58 

50,600 

3,015 

4 

June 30 

52:49 

3667 

21 

55 

146 

178 

55,280 

3,200 

5 

July 10 

63:37 

3679 

50 

53 

123 

105 

54,000 

3,582 

6 

Aug. 5 

75:26 

4372 

50 

57 

195 

385 

55,500 

2,659 

7 

Aug . 1 5 

71:00 

4132 

58 

58 

170 

165 

52,100 

3,100 

8 

Sept. 17 

62:54 

3616 

72 

59 

112 

61 

51,100 

3,850 

9 

Sept. 26 

63:12 

3729 

44 

57 

190 

16 

51,600 

3,810 

10 

Oct. 5 

55:35 

3620 

56 

60 

79 

29 

50,000 

3,800 

Total 

646:03 

38307 

484 


2265 

1057 



Average 

64:36 

3831 

48.4 

56 

226.5 

105.7 




*1.0 naut mi = 1 . 852 X 10 ^ m. 1.0 lbm = 4 . 536 X 10* kg 


58 










TABLE 18 - SUMMARY OF HINDENBURG'S 1936 NORTH ATLANTIC 
SERVICE (EASTWARD CROSSINGS) * 


Flight 

No. 

■ -i 

Date of 
Departure 


Flight 

Time 

Distance 
Nau .Miles 

Passengers 

Crew 

Mail 

Kg 

Freight 

Kg 

Fuel Oil 
Kg 

Lub .Oil 
Kg 

1 

May 11 

49:13 

3600 

50 

55 

824 

75 

— 

59,230 

4,000 

2 

May 2 0 

48:08 

3560 

57 

54 

185 

1096 

55,330 

3,400 

3 

June 23 

61:05 

3504 

57 

54 j 

207 

106 

55,800 

2,800 

4 

July 3 

45:39 

3448 

54 

55 

140 

180 

55,250 

2,800 

5 

July 14 

60:58 

3918 

57 

53 

156 

68 

46,200 

3,552 

6 

Aug. 9 

; 42:52 

3633 

54 

57 

140 

650 

50,250 

3,840 

7 

Aug. 19 

43:49 

3532 

57 

58 

140 

136 

50,000 

3,435 

8 

Sept. 21 

55:36 

3628 

48 

59 

128 

55 



9 

Sept. 30 

58: 02 

3590 

39 

57 

236 

70 

51,000 

3,810 

10 

Oct. 9 

52:17 

3570 

49 

60 

156 

55 



Total 

517:39 

3598 3 

522 


2312 

2391 



Average 

51:45 hrs 3598 

52.2 

56 

231.2 

239.1 



& 

1.0 naut 

mi = 1 . 85 X 10 

m, 1 16m 

i - 4. 536 y 10" 

1 kg 





2. Total expense for North .tlantic flights (1936$) 

a. From Table 15, the total distance flown in 1936 was 
308, 323 km; therefore, the fixed charge per mile 
for 1936 was #771, 950/(3. 083 X 1 0 8 meter), or 

#0. 0025 per meter. 

b. The total fixed charge for the North Atlantic 

g 

flights (a distance of 1.38x10 m) was 

(1. 38 X 10 8 m) (#0. 0025/m) = #345,000 

3. Total variable charges westbound (1936#) 


a. 

223, 532 cubic meters of hydrogen 

0 14, 960 

b. 

367, 792 kg of diesel oil 

0 10, 136 

c. 

15, 240 kg of lubricating oil 

0 5,400 

d. 

Food for crew and passengers 

0 13,200 

e. 

Ground crew at Frankfurt, ground 
transportation of payload, miscel- 
laneous expenses and terminal 



fees 

0 48, 400 


Total 

0 92, 096 


- 59 - 







4. 


5. 


6 . 


Total variable charges eastbound ( 1936$) 


a. 

282, 463 cubic meters of hydrogen 

$ 20, 850 

b. 

399 cubic meters of diesel oil 

$ 9, 495 

c. 

14. 2 cubic meters of lubricating 
oil 

$ 1,875 

d. 

Food for passengers and crew 

$ 10, 000 

e . 

Terminal fees paid to U. S. Navy 
for use of Lakehurst facilities, 
including bases of tank cars and 
freight for hydrogen shipments 
and alterations to equipment at 
NAS 

$ 40, 810 

f. 

Civilian ground crew costs 

$ 1,474 

g- 

Administrative costs including 
office, traveling, insurance, pub- 
licity and other miscellaneous 
expenses at Lakehurst, and in 
New York during 1936; also, ground 
transportation of payloads 

$ 20, 583 


Total 

$105, 087 

Miscellaneous expenses ( 1936$) 


a. 

Passenger insurance 

$ 4, 152 

b. 

Flight pay for crew 

$ 38,640 

c. 

Advertising 

$ 5, 000 

d. 

Expenses charged by passenger agents 

$ 5, 000 


Total 

$ 52, 792 

Total North Atlantic expenses (1936$) 


a. 

Fixed charges 

$345, 000 

b. 

Variable charges (westbound) 

$ 92, 096 

c. 

Variable charges (eastbound) 

$105, 087 

d. 

Miscellaneous charges 

$ 52, 792 


Total 

$594, 975 


The total expense (in 1936$) on the North Atlantic route per one-way trip 
was $29, 749. In 1936, the passenger revenue was a minimum of $18, 108 (1936$) 
and a maximum of $34, 204 one way. Freight and mail revenues (principally 
mail) undoubtedly covered the total expense of $29, 749 (1936$), assuming that 
passenger revenue did not. 


- 60 - 



Table 19 summarizes the operating costs for the 1932 Graf Zeppelin and 
1936 Hindenburg commercial service. Reference 17 indicates that the cost 
per available seat mile for the LZ-129, which apparently is based on not con- 

ct 

sidering mail revenues , is $0. 16; this is the same value obtained from the 
above data when mail revenues are neglected. 


TABLE 19 - ZEPPELIN COMMERCIAL PASSENGER 
SERVICE OPERATING COSTS * 



1932 GRAF ZEPPELIN 
SOUTH AMERICAN 
SERVICE (1932?) 

1936 HINDENBURG 
NORTH ATLANTIC 
SERVICE (1936$) 

ITEM 

Discounting 
Mail & 
Freight 
Revenue 

Accounting 
for Mail 
& Freight 
Revenue 

Discounting 
Mail & 
Freight 
Revenue 

Accounting 
for Mail 
& Freight 

Revenue (Est) 

1 . Block Speed 
(MPH) 

63.3 

63.3 

64.1 

64.1 

2. Stage Length" 

(Statute Miles) 

5487 

5487 

3715 

3715 

3. Available seats 

20 

20 

50 

50 

4. Total Operating 

Expense for Given 
Stage Length ($) 

19,500 

7,920 

29,749 

29,749 

5. Cost/Average 
Seat Mile 
($/Statute Mile) 

0. 18 

0.07 

0.16 

0.10 

6. Cost/Hour ($/Hr) 

225 

91.37 

513 

312 

7. Cost/Mile 

(^/Statute Mile) 

3.55 

1.44 

8.01 

4.87 


* - 1 3 

1 . 0 mph = 4.4 70 x10 m/s, 1.0 statute mile = 1 . 609 X 1 0 m 

** 

See Appendix C of Volume IV for added details on commercial service from 
which South American and North Atlantic block speeds and stage lengths 
have been determined. 


Mail revenues were subsidized, the exact extent of which has not been 
established during this overview exercise. 


61 




It is impractical to determine by analyzing raw data what the cost per ton- 
mile of cargo for the Graf Zeppelin and Hindenburg would have been had they 
been cargo transporters rather than passenger ships. The detailed weight 
statements of the airships must be analyzed and passenger-related equipment, 
accommodations, and allowances removed. In addition, the impact of provid- 
ing a cargo hold capability must be accounted for. The realization that passen- 
ger meals, entertainment, and stewards would not be required also must be 
considered in terms of reduced crew size and labor as well as resulting increases 
in payload. Additional costs also would be incurred in loading and unloading. 

As to what the cost might have been per ton mile, an analysis by Goodyear 

in 1944 and 1945 that is based directly on the Hindenburg operating expenses 

indicates that a cost of $0. 16 per ton-mile (1945 dollars) would have been 

5 

reasonable for a 2. 83Z X 10 cu m (10, 000, 000 cu ft) helium ship. 

Members of the International Zeppelin Transport Corporation (Reference 
18) include Goodyear Zeppelin Corporation; G. M. -P. Murphy and Company; 
Lehman Brothers; United Aircraft and Transport Corporation; Aluminum Com- 
pany of America; Carbide and Carbon Chemicals Corporation; and National 
City Company. On 24 March 1930, an agreement was signed by Dr. Hugo 
Eckener, president of Luftschiffbau Zeppelin, P. W. Litchfield, president of 
The Goodyear Tire & Rubber Company; J. C. Hunsaker, vice president of 
Goodyear Zeppelin; and J. P. Ripley, vice president of National City Company, 
to cooperatively pursue the study, development, establishment, and operation 
of a North Atlantic airship transport line. 

During an October 1930 conference in Friedrichshafen between Mr. Hunsaker 
and Dr. Eckener, it was decided to halt construction of a 40-passenger 141,600 
cu m (5, 000, 000 cu ft ) hydrogen-filled airship (LZ- 128) and redesign a larger 
airship, the LZ-129 (Hindenburg), that could be operated with helium. During 
this same conference, Dr. Eckener stated he favored diesel engines and later 
announced the new ship would definitely have diesel engines. 

However, the Helium Act of 192 5, which stated that helium could not be 
exported as a rare military asset, was expected to be relaxed but wasn't and 
accordingly the Hindenburg of necessity had to use hydrogen. After the Hinden- 
burg loss in 1937 due to combustion of leaking hydrogen, the German govern- 
ment suspended further commercial operations until helium could be obtained. 


- 62 - 



Thus, LZ -128 (Graf Zeppelin) and LZ-130 (Graf Zeppelin II) were idled (JLZ - 
130 was used by the military on a limited basis with hydrogen). Meanwhile, 
L-Z's plans for LZ-131 and LZ - 1 32 continued to develop. It appeared at first 
that Congress would liberalize the Helium Act. Hitler's march into Austria in 
1938, however, eliminated the possibility of the Germans receiving helium 
from America. The two remaining airships in Germany, the LZ-127 Graf Zep- 
pelin and the LZ-130 Graf Zeppelin II, were taken over by the military and 
scrapped in order to use the aluminum in World War II aircraft. 

As noted earlier, the metalclad is of interest in the context of a modern 
airship configuration. Rather in-depth economic analyses performed by the 
Detroit Aviation Company (Reference 7) are available for detailed considera- 
tion in Phase II; therefore, this subject is not discussed. 

Manufacturing 
Rigid Airships 

Rigid airships were the first large aircraft. As a result, many problems 
encountered later in the manufacture of heavie r -than-air (HTA) vehicles were 
first revealed during the German rigid airship program. Certain classes of 
the Zeppelin World War I airship approached production quantities. Enough 
were manufactured so that learning curve effects were identifiable. Near the 
end of the war, the Zeppelin Company was building 56, 640 cu m (2, 000, 000 
cu ft) rigid airships at a rate of one every six weeks. 

Development times for past airships have depended upon a variety of inter- 
related considerations such as the current state of the art as related to the de- 
sign objectives of the project, the particular expertise and experience of the 
agency designing the vehicle, and the size of the engineering and design team 
applied (which was often dependent upon national priorities). In general, pro- 
grams like the Akron and the Hindenburg, which were first units of a given 
design, required three to four years prior to first flight. The Germans during 
World War I had reduced this time from two to six months. However, their 
new designs were somewhat an extension of prior proven vehicles. 

Reference 8 points out that the Zeppelin World War I production experi- 
ence would suggest an 80 percent learning curve as being applicable to large 


- 63 - 



rigid airships. This value is somewhat typical of HTA manufacturing experi- 
ence. It is also similar to the 83 percent factor applied by Goodyear in their 
I944 - 1945 cost estimate of six 2, 832 x 10~* cu m (10, 000, 000 cu ft) commercial 

airships. This estimate reflected increased use of tooling and jigging than in the 
Zeppelin construction; accordingly, a slightly higher factor was applicable . Although, 
less learning takes place when increased mechanization is introduced, the 
average cost of a given lot size is reduced due to lower cost of the initial unit. 

Table 20 gives a detailed breakdown of the actual hours and costs associ- 
ated with the Akron and Macon rigid airship programs. Far greater than an 
8 0 percent effect occurred between the Akron and Macon airships. However, 
this effect should not be regarded as typical because, at the time of the con- 
struction of the Akron, manufacturing expertise was not available in this coun- 
try. Thus, the Akron was constructed on a less productive basis than would 
have occurred if the new design of the Akron had been the only variable for an 
experienced manufacturing team. 


TABLE 20 - DETAILED BREAKDOWN OF ACTUAL AKRON AND MACON 
PROJECT HOURS AND DOLLARS (AS OF DATE INCURRED) 



AKRON 

[ MACON 

I AKRON 

I MACON 

I AKRON 

1 MACON 

I AKRON 

1 MACON 

1 AKRON 

• MACON 


H0U 

RS 

j LABOR 9 

j OVERHEAD 9 

| MATERIAL 

! TOTAL# 

Fabrication 

1,500, 000 

938, 190 

1 , 343, 320 

678, 104 

718, 547 

504,886 

1, 244,097 

911 , 344 

J, 305, 964 

2,094 ,334 

Design 

408,000 

119,740 

482,231 

146 , 757 

235,331 

35,311 

19,845 

17,775 

737,407 

199,843 

Research & Tests 

138 , 750 

48, 300 

152 ,623 

48,167 

128,670 

28, 186 

86,775 

9, 368 

368 , 068 

85,720 

Inflation 

6 , 940 

4,855 

5,213 

3,039 

6,361 

2,265 

2,072 

8,943 

13,646 

14,247 

Trial Flights 

9,842 

17,873 

9,842 

15,505 

13,288 

8, 356 

28, 550 

29,426 

51,680 

53,288 

Unused Stores 







-0- 

26, 290 

-0- 

26, 290 

Tools & Devices 

i 




254,190 

136, 262 



254,190 

136, 262 

Taxes 





38,415 

30, 750 



38,415 

3^, 750 

tquipment Depreciation 





90,113 

96, 905 



90,113 

96, 905 

Insurance 





60,060 

41 , 668 



60,060 

41,668 

P e r f . Bond 





2,687 

1,225 



2,687 

1,225 

Dock Depreciation 





1 ,224,267 

-0- 



1 ,224, 267 


Total 

2,163,532 

1 , 128 ,908 

1,993,229 

891,572 

2 , 7 71,929 

885,813 

1,381, 339 

1 , 003,146 

6,146, 497 

2,780,531 

Admin. Exp. 






129,970 



148,433 

129,970 

Total Cost 






1,015, 783 



6, 294,930 

2,910,501 


64 - 



Table 21 summarizes rigid airship manufacturing data. 

Figure 17 shows the data of Table 21 relative to the direct construction 
man-hours per pound of empty weight as a function of gas volume (total). As 
noted in Table 21, all data are for the first unit of a new design. All commer- 
cial and many of the military airships fall near the suggested "historical aver- 
abe" value that has been included in the figure. The only noticeable departures 
would include: German Zeppelin LZ-38; German Zeppelins LZ-62, LZ-91, 

LZ -95, and LZ-100; and British R-100. 

As to why this departure occurred, Reference 1 suggests that the LZ-38 
type was the first airship sufficiently developed for war in terms of altitude, 
armament, and speed. Reference 1 also reports that the LZ-38 was very suc- 
cessful from the summer of 1915 to the spring of 1916. 

The increase in man-hours per pound that the ever-increasing military 
requirements resulted in is clearly stated in Reference 1. In Reference 1, 
when referring to prior Zeppelins in comparison to LZ-62, the statement is 
made that "in this connection the main advantage of the former type (prior to 
LZ-62), namely the employment of a large number of similar cells and the 
rapid quantity production of the transverse frames or rings, was relinquished 
in favor of greater airship speed. " Other military demands such as quieter 
exhaust systems, multimachine gun locations, more elaborate bomb releases, 
improved structural techniques (requiring more hand labor) to permit higher 
altitudes, and navigational improvements required to traverse greater distances 
all added to the man-hours or cost per pound. 

The military airships of other nations never performed these "strategic 
missions"; accordingly, their construction man-hours per pound never ap- 
proached the value of the elaborate German warships. 

The 1944 Goodyear estimate for direct construction man-hours for the 

5 

initial unit of its proposed 1 944 design of a 2.832 x 10 cum (10,000,000 
cu ft) commercial airship agreed closely with the suggest historical average. 

The fabrication man-hours per pound for this airship were somewhat lower 
than the historical average; however, the estimate reflected added tooling and 
jigging with respect to that used in prior programs. Accordingly, a lower 
initial unit estimate and an 83 percent learning curve were used as opposed 
to the historical 80 percent curve. 


- 65 - 



TABLE 21 - SUMMARY OF RIGID AIRSHIP MANUFACTURING DATA 



L » 


66 




Table 21 compares data for the LZ-129 and L,Z-130, which were essential- 
ly the same design. This table lends further credence to the 8 0 percent learn- 
ing curve effect experienced with the World War I Zeppelin. 

Thus, the historical average suggested in Figure 17 is a reasonable point 
of departure for Phase II in establishing future rigid airship acquisition costs. 
Readily available information relative to existing materials, existing propul- 
sion systems, and existing avionics costs will provide realistic information 
for other facets of the acquisition cost estimate. 

It is important to realize that, given today's technology in HTA and the 
historical foundation up through the 1940*s in LTA, Goodyear envisions a 
modern rigid airship that would not require any state-of-the-art advances. 
Certain factors such as compliance with today's certification standards and 
substantial aerodynamics and structural verification testing must be considered. 
Certain costs typical of many new HTA programs are avoidable because of the 
off-the-shelf component philosophy, which seems realistically adaptable, and 
more importantly because in no area must the state-of-the-art be advanced. 

Non-rigid Airships 

Two periods of manufacturing activity illustrate the approximate fabrica- 
tion costs of past military non-rigid airships: (1) the World War II years 
during which the K-type airships were built and (2) 1950 to I960, during which 
the more elaborate ZSG-4, ZS2G-1, ZPG-2, and ZPG-3W were built. 

Prototype airships (one each) were built of the ZSG-4, ZSG-1, and the 
ZPG-2 with follow-on production orders of 14, 17, and 15, respectively. Four 
ZPG-3W configurations were delivered. Table 22 summarizes pertinent cost 
data relative to these configurations. Based on the fabrication dollars* and 
empty weight data of Table 22, a cost per pound factor is given for both the 
prototype and production quantities. A learning curve factor also is given 
and was derived on the basis of the prototype cost, the average production 
cost per unit, and the number of units produced. The learning factors are 
higher (less learning is indicated) because material dollars are included in the 
cost-per-pound information. Material dollars vary little from unit to unit. 

All ZPG-3W units are considered prototype due to limited quantity manufactured. 


Dollars are used for the non- rigid air ships and hours are used for 1 he rigid. Hours 
are used in the rigid to avoid the uncertainty of exchange rates, short term 
inflation effects, etc. 


- 67 - 




68 


Figure 17 - Direct Construction Man-Hours for Past Rigid Airships 

(First Unit of New Design) 




TABLE 22 - FABRICATION COSTS FOR NON-RIGID AIRSHIPS 









Figure 18 shows the prototype cost -per -pound data versus empty weight 
both at the incurred value as well as at the 1974 dollar level. Because four 
ZPG-3W's were built compared to one each of the other configurations, the 
ZPG-3W cost per pound is somewhat lower in terms of the 1974 common 
dollar basis. As a result, the cross-hatch in Figure 18 - which indicates 
a historical cost-per -pound range for a first-unit military prototype - ex- 
cludes the ZPG-3W data point. Phase II must necessarily identify propulsion 
system, avionics, and electronics requirements based on specific mission 
requirements; costs for these items are additive. However, with that data 
and the data in Figure 19, acquisition of a military prototype should be reli- 
ably identifiable. A nonmilitary prototype would be considerably less than a 
military prototype, which is perhaps better indicated in Figure 19. 

Figure 19 shows production costs for non-rigid military airships 
although there are differences in terms of the magnitude (and, as a result, 
in the techniques utilized) of airship production in comparison with HTA pro- 
duction. Figure 19 shows that: 

1. There is a substantial difference between the World War II 
K-type configurations and the configurations following the 
war in terms of the common 1974 base due to increased 
military complexity as well as a quantity effect. This 
trend also is discernible in HTA military aircraft and is 
identifiable from the data presented for these vehicles. 

The military HTA cost-per -pound increase indicated from 
1955 to 1967 is 350 percent, which converts to a real 
dollar -per -pound growth of 300 percent. 

2. Mid- 1950 military LTA and HTA costs per pound were on 
the same order as indicated in Figure 19, although the 
different comparison base suggests HTA vehicles exhibited 
a somewhat lower cost per pound. 

3. Commercial HTA costs per pound are about one-third the 
cost per pound of the military HTA in terms of real 
dollars. This same trend will exist for LTA, with the 
extent of the factor a task to be performed in Phase II. 


- 70 - 



DATA FROM TABLE 22 


=> = 
o o 

Cl. Cl 


QC O 


O XZSG-4 (QUANTITY * 1 ) 
□ XZS2G-1 (QUANTITY * 1 ) 
A ZPG-1 (QUANTITY = 1 ) 
V ZPG-3W (QUANTITY = 4) 



0 10 20 30 40 50 60 70 


AIRSHIP EMPTY WEIGHT - POUNDS x 10' 3 

1- ENGINES AND MILITARY ELECTRONICS G.F.E.; MATERIALS INCLUDED 

2. DOES NOT INCLUDE SPARES. 

3. WHOLESALE PRICE INDEX USED TO ESCALATE. ( SOURCE IS U.S. BUREAU 
OF LABOR STATISTICS. ) 


Figure 18 - Manufacturing Costs for 
Non-rigid Airships (Prototype) 


o 

ZSG-4 1 * 3 

(QUANTITY = 

■ 14) 

□ 

ZS2G-1 1 ,3 

(QUANTITY * 

' 17) 

A 

ZPG-2 1 * 3 

(QUANTITY * 

■ 15) 

O 

K9-K50 

(QUANTITY - 

■ 42) 

o 

K50-K135 

(QUANTITY = 

■ 85) 


42) WW II N0N-RIGIDS 


DATA FROM TABLE 22 



1. ENGINES AND MILITARY ELECTRONICS G.F.E; MATERIALS INCLUDED 

2. WHOLESALE PRICE INDEX USED TO ESCALATE. (SOURCE IS U.S. BUREAU OF LABOR STASTICS.) 

3. DOES NOT INCLUDE SPARES. 

4. DOES INCLUDE SPARES. 


Figure 19 - Manufacturing Costs for 
Non-rigid Airships (Production) 


71 




The type of data presented in Figures 18 and 19 will be of significant 
assistance in establishing realistic acquisition costs in Phase II. 

Table 23 summarizes engineering hour expenditures on the ZPG-1, 
ZSG-4, ZS2G-1, and ZPG-3W programs. This data is not analyzed in this 
report but should be a general guideline for Phase II. 


Prior Goodyear Economic Studies (1944$) 

Figure 5 shows that various rigid airship projects have continued at Goodyear 
Aerospace since the Akron and Macon era. In the mid- 1940*8, Goodyear Aero- 
space conducted an extensive design and economic study relative to six large air- 
5 

ships Z.832 X 10 cum (10, 000, 000 cu ft) in both a cargo and passenger trans- 
portation role. The following paragraphs describe the results of that study, which 
reflected use of the airship fleet in basically a sea-level capacity. The cost 
estimate was based on the actual cost of prior airships. 

Commercial Passenger 

Table 24 summarizes the total cost of the six airships. Thus the average 
total cost of one airship on the basis of six produced (over a 60 month period) 
is about 7*4 million (1944 dollars). In the analysis conducted at that time to 
determine the required passenger fares and cost per ton mile, the airships were 
conservatively assumed to cost $ 8 million. The following study was made to 
determine the passenger revenues required to support an airship passenger service. 

Investment Required 

One 2.832 x 1 cu m (10, 000, 000 cu ft) airship $8* 000, 000 


Helium inflation 120, 000 

Powerplants 75, 000 

Radio 100, 000 

Outbound terminal facilities 150, 000 

Total $8,445, 000 


-72 - 



TABLE 23 - ENGINEERING HOURS BREAKDOWN 




— — 

ZPG 

- 1 

ZSG 

4 

ZS2G 

- 1 

ZPG 

3W 

T otal 




Hours 

% 

H our h 

% 

Hours 

% 

Hours 


Hours 

Of t 

Design data and test 












Design 

(D-2 , D-5) 

315. 033 


37 1. 322 


409. 0b4 


616, 72 1 




Ground support 

(F-7| 







7, 673 




De velopment 

(D-8, F-5) 

3,211 




13,440 


27, 365 




Design services 

(D-9, F -4 1 



1, 657 


3, 603 


28. 249 

4 3.6 

1, 797, 938 

43. 7 

3 18, 244 

37. 7 

372. 979 

50. 4 

426, 707 

44. 0 

680, 008 

Stress and weights 

ID-6) 

88, 896 

10. 5 

66, 990 

9. 0 

109, 686 

1 1. 3 

84, 428 

5.4 

350, 000 

8. 5 

Aero and thermo 

(D-7 , F - 3) 

16, 94 1 

2. 0 

4, l 19 

0. 6 

2 1, 455 

2. 2 

39, 2 18 

2. 5 

8 l, 733 

2.0 

Static and mis teat 

(D- 10. 3- 11, F-6) 

78,999 

9.4 

16, 542 

2.2 

55. 223 

5.7 

14 1,695 

9. 1 

292,459 

7. 1 

P light test 

(D- 12) 

94, 609 

11.2 

30, 443 

4. 1 

90. 954 

9. 4 

131, 773 ! 

8. 4 

347, 779 

H. 5 

Final corr data 

ID- 13) 

3, 340 

0. 4 



2, 185 

0.2 

41, 708 

2. 7 

47, 2 33 

1. 1 

Detail spec and project 

eng 1 D - 1 . D-4 1 

2, 531 

0. 3 

4. 642 

0. 6 

3, 455 

0. 4 

17, 969 

1.2 ! 

28, 597 

0. 7 

Mockup 

(D- 3) 

31, 3 15 

3. 7 

43, 46 1 

5.9 i 

3 1, 798 

3. 3 

29, 642 

1.9 

136,2 16 

3. 3 

F abrication 












Design coordination 

(F - 1) 

163,520 

19. 4 

l r -9, 017 

2 1.5 

162, 428 

16. 7 

2 12, 916 

13. 7 

697,88 1 

17.0 

Stress and weights 

(F -2 ) 



9. 044 

1. 2 

22, 893 

2.4 

60,025 

3. 8 

91,962 

2.2 

Publications 

(F-8) 

45, 343 

5. 4 

32, 140 

4. 3 

43, 993 

4.4 

1 18, 473 

7. 6 

239, 949 

5. 8 

Field service 

(F-9) 



1, 054 

0. 2 

10 


2,000 

0. 1 

3,064 

0. 1 

Total engineering 

843, 738 

100. 0 

740, 431 

100. 0 

970, 787 

100. 0 

559, 855 

100. 0 

4, 1 14, 8 1 1 

100. 0 


TABLE 24' - COST OF SIX 
10, 000, 000 - CU FT 
AIRSHIPS (1944?) 


Item 

Cost (S) 

GAC engineering and design 

5, 561, 058 

GAC manufacturing 

13, 196, 910 

GAC tooling 

3, 528, 142 

GAC inspection 

1, 043, 328 

GAC overhead (labor only) 

6, 729, 525 

GAC overhead (building depreciation included) 

10,2 13,229 

Trial flights (labor only) 

176, 000 

The Goodyear Tire it Rubber Company 
(including manufacture of outer cover 
and gas cells plus installations) 

4, 526, 872 

Administrative (i% of factory cost) 

449, 75 1 

Total cost ($) 

44,423, 815 

Average cost per unit {$) 

7,403, 969 


Opf^4l p 


- 73 - 


Annual Fixed Cost 


Depreciation, flight equipment 

(12-1/2%), and facilities 


$ 1, 055, 630 

Insurance on ship (5%) 


422, 250 

Maintenance and repair 


100, 000 

Interest on investment (2-l/2%) 


211, 130 


Total 

$ 1, 789, 010 

Annual Operating Costs 


2500 mi* 

35 00 mi* 

Salaries 

$ 277, 800 

$ 277, 800 

Fuel and oil 

239, 618 

189, 600 

All meals 

91, 728 

67, 392 

Hangar ground crews, etc. 

148, 000 

98, 000 

Helium purification 

17, 600 

17, 600 

Compensation 

4, 139 

4, 139 

Passenger and baggage liability 
insurance 

53, 543 

18, 207 

Advertising, sales, 
administrative 

200, 000 

200, 000 

T otal 

$ 1, 042, 426 

$ 872,738 

Recapitulation 


2500 mi * 

3500 mi v 

Total operating costs 

$ 1, 042,426 

$ 872,738 

Total fixed costs 

1, 789, 010 

1, 789, 010 

8% profit on investment 

675, 600 

675, 600 

Total cost 

$ 3 , 507, 036 

$ 3 , 337, 348 


Thus, to produce sufficient revenue to permit meeting indicated costs and 
show an 8 percent profit (before taxes), the following fares can be charged on 192 
one-way trips per year for a 4. 023 X 10 m (2500 mi) flight and 92 one-way 
trips pe r year for a 5 . 632 X 10^ m (3500 mi) flight: 

3 

1.0 statute mile = 1.609 X 10 m 


- 74 - 


Passengers per year 
(one way) 


75% 

Ship type occupancy 

2500 mi* 

3500 mi 

Deluxe 

84 

16, 128 

8, 064 

Pullman 

174 

33, 408 

16, 704 

Economy 

2 16 

41, 472 

20, 736 

Ship miles per year 


480, 000 

336, 000 

Yearly utilization (hr) 


6, 000 

4, 2000 

Direct operating cost 
per ship mile 


$2. 17 

$2. 60 

Total all-inclusive operating 
cost per ship mile 


$7. 31 

$9. 93 

Passenger miles per year 




Deluxe 


40, 320, 000 

28, 224, 000 

Pullman 


83, 520, 000 

58, 464, 000 

Economy 


103, 680, 000 

72, 576, 000 

Direct operating cost 
per passenger mile is: 




Ship type 


2500 mi* 

3 5 00 mi 

Deluxe 


0. 0258 

0. 0309 

Pullman 


0. 0125 

0. 0149 

Economy 


0. 0101 

0. 0120 


❖ 


sjc 


The total all-inclusive operating cost 
(including profit) brings the following 
one-way fares: 

Per passenger 

Per passen- , mile at 75% 

Ship type Z 5 00 mi ^ ger mile 3500 mi ‘ load factor 


Deluxe 

Pullman 

Economy 


$217.45 $0.0879 

104.98 0.0420 

84.56 0.0338 


$413. 86 $0. 1182 

199. 79 0.0571 

160.94 0.0460 


The total all-inclusive operating costs appear to be in line with the 
Hindenburg costs presented earlier. Since the load factor was higher on 

the Hind enburg and Graf Zeppelin than in this analysis and since the 

*1.0 statute mile = 1.609 X 1 0^ m 

- 75 - 


for these two German airships were considerably higher, it appears that the 
economics of the passenger service were viable. 


Commercial Cargo 

A similar analysi s was made in 1944 for the use of six airships as com- 
mercial cargo transporters: 

Summary from Passenger Revenue Analysis 

Total investment $8,455, 000 

Annual fixed costs $1, 789, 010 

Annual Operating Costs 


2500 mi 3500 mi 


Salaries 

$ 180, 000 

$ 180, 000 

F uel and oil 

239, 616 

189, 600 

Crew meals 

28, 800 

2 1, 200 

Hangar, ground crews, etc. 

136, 400 

83, 900 

Helium purification 

17, 600 

17, 600 

Compensation 

4, 139 

4, 139 

Cargo, crew, insurance 

61, 030 

6 1, 030 

Administration, sales, advertising 

200, 000 

200, 000 


$867, 585 

$739, 969 

Recapitulation 


2500 mi 

35 00 mi 

Total operating cost 

867, 584 

739, 969 

Total fixed costs 

1, 789, 010 

1, 789, 010 

8% profit on investment 

675, 600 

675, 600 

Total cost 

$3, 332, 195 

$3,228, 579 


- 76 - 



Trips per year (one way) 
Cargo (lb) per trip 
Ship miles per year 
Ton miles per year 


192 

180, 000 

480, 000 
43, 200,000 


96 

155. 000 

336. 000 

26, 040, 000 


Direct operating cost/ship mile 

2 500 mi 

$ 1. 81 

Direct operating cost/ton mile 

0. 020 

Total operating cost/ship mile 

6. 94 

Total operating cost/ton mile 

0. 077 


3500 mi 

$2.27 
0. 029 
9. 61 
0. 124 


The analysis was then expanded and refined to cover various options then 
of interest. Ton-mile cost comparisons were made with other means of air 
cargo transport of the day (see Figure 20). This figure shows that the airship 
compared very favorably with other forms of air transport. 

The types of comparisons in Figure 20 will be of interest in Phase II. 


American Military Experience (1916 to 1961) 

During World War I, America operated three airship bases in Britain and 
one in France. It is reported, however, that no American blimps were used. 

A limited number of submarines were reported off the U.S. Atlantic Coast and 
bombs were dropped. The primary purpose of the U. S. -built blimps during 
World War I was to train crews, with patrol a secondary role. Following 
World War I, the U.S. Navy's interest turned to the rigid airship, of which 
the Navy ultimately operated five*. 

The operations assigned to rigid airships with the fleet did not develop the 
airship's most promising roles, that of strategic scouting or information seek- 
ing and airplane carrying. The Akron and Macon operated for about 1 700 hours 
each and the Los Angeles for 2800 hours. The operational assignments of the 

The Shenandoah, the British R-38, the Los Angeles, the Akron, and the 
Macon. Reference 17A gives a comprehensive history of rigid airship 
developments within the U.S. Navy. 


- 77 - 













airships mainly were tactical, with the airships supporting surface vessels 
in simulated proximity to combatant areas. 

The uses of rigid airships to carry airplanes in varying numbers were set 
down in a memorandum from Rear Adm. E. J. King, then Head of the Bureau 
of Aeronautics, to the Secretary of the Navy on 12 February 1940: 

1. Scouting 

a. Search operations at long ranges 

b. Contact scouting (strategic) 

c. Observation 

d. Reconnaissance 

2 . General 

a. Neutral patrols 

b. Locating enemy commerce raiders 

c. Convoying merchant vessels 

d. Locating mines and submarines 

e. Bombing (by planes) under certain conditions 

3. Miscellaneous 

a. Radio station calibration, as radio relay, 
direction finding, etc. 

b. As special communication station 

c. Transport of special personnel or supplies 

d. As "assisted takeoff" means for overloaded 
airplanes 

e. Flight research laboratory 


At the time of Pearl Harbor, the U.S. Navy had 10 non-rigid airships, 
six of which were suited for service at sea. A Japanese submarine sank the 
S.S. Medio off the coast of California on 20 December 1941 and attacked oil 
derricks at Santa Barbara, Calif., on 23 February 1942. Ships ultimately 
were being sunk faster than they could be replaced. Based upon the success 
of World War I blimps, the Navy's blimp force was rapidly increased. 


-79 



In the Atlantic and Gulf coastal waters of the United States and in the 
coastal waters of the Caribbean, eastern Central America, and Brazil, 532 
vessels were sunk but none were sunk under escort of an airship. 

In addition to an increase in airships from 10 at the time of Pearl Harbor 
to more than 165 at the close of the war, huge increases in personnel also 
occurred (from 130 in 194 1 to more than 10,000 in 1944). Airship squadrons 
were stationed at Lakehurst, N. J. ; Richmond, Fla.; Trinidad, B.W.I.; 
Recife, Brazil; Key West, Fla.; Moffett Field, Calif.; and Port Lyantey, 
French Morocco. 

5 

At the peak of ope rations , U. S . Navy airships patrolled about 2.787x 10 sq 
m(3, 000, 000 sq mi) of the Atlantic, Pacific, and Medite r ranean coasts. In all, 
airships escorted 89, 000 ships while making 55, 900 flights totaling 550, 000 flight 
hours . 

Only one airship was lost due to enemy action and only after its bombs 
failed to release while the airship was directly over the submarine. The 
blimp was hit by machine gun fire, with a resulting slow loss of helium caus- 
ing the airship to float to the surface. All of the crew was rescued the next 
day except one. 

The wartime uses of blimps, in addition to their major use in escort and 
antisubmarine patrol operations, are listed below. 

1. Search operations 

Friendly submarines in reported areas 
Overdue or lost surface craft 
Crashed planes and survivors 
Survivors of torpedoed or wrecked vessels 

Crew of destroyed U-boat; located by blimp after 
48-hour unsuccessful search by planes and surface 
craft 

Convicts escaping by boat from South American 
penal colony 

Fisherman at sea located and draft summons de- 
livered him by blimp 

Escaped prisoners of war 


- 80 - 



Several boat loads of survivors from sunken German 
blockade runner that were rounded up and guarded 
until arrival of surface craft. 

Uncharted sunken vessels 
Obse rvation 

Oil and air leaks from new or overhauled U.S. sub- 
marine s 

Harbor antisubmarine nets and other items 

Speed and other trials of naval vessels 

Maneuvers of PTs, landing craft, minesweepers, and 
other types 

Amphibious training operations for Army and Navy 
personnel 

Rocket firing and shell bursts for BuOrd 

Underwater explosion tests 

Effectiveness of coastal and city blackouts 

Inspection of damaged surface craft to determine salvage 
pos sibilitie s 

Inspection of Brazilian jungles and military installations 
by Brazilian officials 

Inspection of hurricane damage 

Army tank maneuvers 

Results of Army long-range gun firing tests 
Operational training of fleet units 
Inspection of naval stations and activities 
Photography 

Merchant vessels, for identification purposes 

Men-of-war, for identification purposes 

Submarine operations, for instruction purposes 

Classified special projects for BuOrd and other 
departmental units 

Airplane maneuvers 

Speed and turning trials of surface craft 
Surface craft maneuvers 

Amphibious exercises, for training films 
Flight maneuvers of new Army fighter plane 
Prospective real estate acquisitions 

Results of Army gunfire with new fire control equipment 
Army gunnery exercises 



Hurricane damage 
Landfalls, for aviators' training 
Inlets and channels, for Coast Guard 
Landslides, for highway authorities 
Disabled destroyer, for BuShips 
Fall of shot in gunnery exercises 

Enemy mine adrift off coast, for identification purposes 

4. Mine operations 

Spotting mines and mine fields, and plotting locations 

Direction of and assistance to surface craft in mine 
sweeping activities 

Destruction of surfaced mines by gunfire 

Warning and diversion of surface sweepers standing into 
mine danger 

Warning and diversion of unescorted surface craft from 
floating mine 

5. Rescue operations 

Rescue of plane-crash survivors from isolated island 
beach 

Rescue of plane-crash survivors from the sea 

Rescue of plane-crash survivors from Brazilian jungle 

Rescue from isolated beach of survivors of torpedoed 
ves sel 

Rescue from desert of stranded rescue party plus re- 
moval of body of plane-crash victim 

Coverage of carrier flight training exercises and location 
of and assistance to ditched aviators therefrom 

Location and marking men overboard 

Rescue patrol during joint Army-Navy Frontier defense 
exercises 

Rescue patrol in areas of dense air activities 

Search for and location of sunken merchantmen survivors 
known to be adrift 

6. Assistance to vessels and persons 

Location of disabled surface vessels and direction of 
salvage craft to them 

Location of convoy stragglers or late-comers, and their 
direction to junction with convoy 


- 82 - 



Emergency diversion of surface craft from shoals 

Guidance of surface craft through fog-bound harbor 
entrances 

Guidance of buoy-tenders to uncharted wrecks 

After survey of abandoned torpedoed merchantmen, 
blimp called for tow, directed crew to return aboard; 
merchantmen consequently saved 

Coverage of cable ship while making cable repairs 

Shipping control, convoy formation and dispersal, by 
carrying shipping controller and delivering oral or 
written orders at sea or off port 

Prevention of inevitable collision of two convoys, still 
visually separated 

Location of barges broken adrift and effecting their 
recovery by towing vessel 

Delivery of written or oral orders to men-of-war and 
merchantmen at sea, during radio silence 

Delivery to shore of messages received visually from 
merchantmen at sea 

Delivery ashore of urgent message received visually 
from damaged merchantmen at sea requesting immediate 
docking upon arrival 

Relay of message to have ambulance awaiting upon arrival 
of surface vessel in port 

Landing on carrier at sea, picking up confidential matter 
and delivering it ashore 

Location of favorable firing area for vessels conducting 
A. A. exercises 

Effecting rendezvous between escort vessels and friendly 
submarines 

Effecting junction of surface escorts and convoys in bad 
weather 

Furnishing position to bewildered surface craft 

Lowering of medical officer from airship to surface 
vessel to treat seriously ill crewman 

Delivering confidential matter on deck of carrier at sea, 
for use by General Doolittle's air-raid on Tokyo 

Towing disabled Army launch out of danger of going 
aground in neutral territory 

Delivering gasoline to Army crash boat on a rescue 
mis sion 


- 83 - 



Delivering 50-gallon drums of gasoline to PBY stranded 
on beach 

Delivery of food, water, medical supplies, etc. to sur- 
vivors at sea 

Emergency transportation of injured personnel to hospital 

Location of crashed planes in isolated areas 

Guidance of rescue parties to isolated survivors and 
crash scenes 

Delivery of messages, food and water to salvage party 
on barren island 

Scheduled delivery and pick-up of mail at isolated Coast 
Guard station in Caribbean 

Delivery of medical supplies to remote Coast Guard 
station for treatment of badly burned personnel 

Scheduled delivery of food and water to engineers working 
on emergency landing strip in Brazilian jungle 

Delivery of urgently needed material and transport of 
personnel between stations in South America by BATS 
(Blimp Air Transport Service) 

Coordinated communications for removal of sick seaman 
from a merchant tanker by Coast Guard plane 

Delivered Army aerologist and equipment to isolated post 

Coordinated salvage operations by surface craft in case 
of grounded transport 

Escorted vessel that reported damaged, compass to 
Columbia River lightship 

Sighted Army tug aground, lowered survival kit and stood 
by until rescue surface craft arrived 

Sighting and reporting of surface craft in distress, stand- 
ing by until arrival of surface aid and homing latter 

Sighting and reporting of unmanned surface craft at sea, 
standing by until arrival of surface aid 

Sighting of burning vessel at sea, summoning and homing 
surface aid 

Guided rescue party to scene of plane crash and illumi- 
nated with blimp's landing light 

Came upon tanker with disabled engines, summoned and 
directed salvage vessel to it 

Hurricane damage to islands and coastline 



Coastline for sites for amphibious training 
Migratory birds for Department of the Interior 
Fire damage in isolated areas 

Radar and RDF calibration assistance, for both ships and 
shore stations 

Weather observation and reporting in Caribbean (and 
other) areas 

Reporting of fires in isolated areas 

Location and reporting of schools of fish 

Tracking and marking torpedoes for recovery, for sub- 
marines and shore units 

Tracking and marking for recovery, torpedoes fired from 
torpedo planes 

Located and directed salvage operations of floating bales 
of rubber from sunken German blockade runners 

Sighting and reporting of floating obstacles dangerous 
to shipping 

Salvage of $37, 000 worth of equipment from crashed 
B-25s in Brazilian jungle, by repeated airship landings 

Dropping of parachute troops and parachute riggers for 
live -jump training 

Trailing banners for Red Cross drives 

Training of HTA personnel in sonobuoy operations 

Sighted floating boiler at sea - a menace to navigation - 
and sank it by gunfire 

Reported malfunctioning of Block Island Sound marker 
light and illuminated it with blimp's spotlight for repair 
party 


Subsequent to World War II, the Navy used.the blimp primarily in an 
antisubmarine warfare and an aircraft early warning capacity. The Navy con- 
cluded its airship activities in 1961. Appendix B of Volume IV summarizes 
the Navy airships procured after World War II. 




- 85 - 



Airship Safety 


Airships are safe for the following reasons: 

1. They have a low landing speed (compared with HTA) 
which is particularly true of conventional LTA, 

2. Multiple engines permit an essentially normal landing in 
the event of engine(s) failure(s). Neutrally buoyant air- 
ships were capable of landing without power under a 
variety of conditions. 

3. Essentially all airships are provided with an emergency 
deballast capability (fuel and water recovered from prod- 
ucts of combustion) in the event that loss of lift begins to 
occur. The ZPG-3W, which was capable of heavy take- 
offs, could release sufficient ballast on an almost 
instantaneous basis (fuel in slip tanks, etc. ) to bring 

the airship into a neutrally buoyant condition if the 
ability to sustain heavy flight was lost. 

4. Rigid airships use gas compartmentalization (individ- 
ual gas cells), which results in two safety related 
features: 

a. Loss of lift, in all but the gravest of emergen- 
cies, is limited to the loss associated with one 
cell being deflated. A deballasting capability 
is provided to retain a neutral buoyancy condi- 
tion during such an occurrence. 

b. The airship structure is designed to accommo- 
date the increase in the maximum static bending 
moment resulting in one gas cell being deflated, 
thus increasing the basic vehicle safety. 

Non-rigid airships have typically used envelopes designed with large 
factors of safety since the gas historically has not been compartmentalized. 
Additionally, these envelopes are tested periodically to verify their continued 
integrity. 


- 86 - 



Non-rigid airships are typically designed with only a small positive pres- 
sure within the envelope in order, among other considerations, to minimize 
fabric stresses, thereby better ensuring structural integrity. The shape of the 
forward portion of the envelope is maintained during flight by radial stiffening 
members (battens) emanating from the nose of the ship (see Figure 2). 

Although never accounted for in the design process, the ability of the non- 
rigid airship to momentarily deflect and relieve the load causing the deflec- 
tion is an added safety feature inherent in the non-rigid design. 

Another aspect of airship safety is it's ability to remain airborne without 
using large quantities of fuel during severe weather that may momentarily pre- 
vent landing. Weather avoidance both enroute and in terms of preflight planning 
has progressed enormously since the days of the last commercial airship ser- 
vice and would make airship operation much safer from the weather standpoint. 
While severe thunderstorms were purposely avoided in prior airship opera- 
tions, airships flew through storm fronts by flying the breaks in the passing 
front. Weather as it affects airship operation is discussed subsequently. 

Although never a problem with past airships due to the number flying and 
location of flights, collision avoidance now requires attention where airships 
are used at and around existing airports and conjested airways. Today’s avi- 
onics and the continual advances being realized in this area are directly appli- 
cable to the design process for a modern airship vehicle (MAY). This fact 
alone minimizes the potential problem of collision avoidance with a MAV. 
Another factor favoring the MAV in this respect is its size, which would lead 
to early identification by nearby aircraft. In addition, the closing speed of an 
airship and nearby aircraft would be minimal by comparison with that of two 
commercial jetliners. 

The suggestion of dedicated airspace that has been made relative to MAV 
use is perhaps a pessimistic generalization. If MAV's were used at the busy 
international airports in this country, the standard practices at these airports 
would have to be interrupted. However, the airship’s potential is best realized 
when it is used at much less sophisticated facilities, thereby reducing door-to- 
door times. In this respect, the dedicated airspace is somewhat academic. 

In order to be most effective from a transportation standpoint, conventional 
airships would fly at low altitudes (nominally below 1524 m (5000 ft) above sea 


levels . 


- 87 - 



Fire hazards in airships from the inflation gas would be non-existent 
today due to the use of helium. 

Another feature available today is thrust vectoring, which can be accom- 
plished by any of several means. Thrust vectoring enhances low speed control 
of the airship in terms of simplifying the approach, landing, and takeoff oper- 
ations and also enhances the safety with which airship operations can be under- 
taken. 

Realizing that many design-related safety features are available and would 
be incorporated into the design of a MAV, it is still essential to review the 
safety record of past airships in order to generate some part of a data base to 
support the contention that a MAV would be a safe vehicle by today's standards. 

German Zeppelin Experience . - During the 1910 to 1914, the 1919, and the 
1928 to 1937 commercial service, not one passenger was injured or killed ex- 
cept for the 13 passengers killed in the Hindenburg crash. Twenty-two crew 
members also were lost with the Hindenburg. 

From 1910 to 1914, service was restricted primarily to fair weather as 
the rigid airship at that time had had a very short history. During that period, 

Q 

37, 000 passengers were carried on 1600 trips, or a total of 5.23 X 10 m 
(325, 000 statute mi), without fatal accident to passengers or crew. The 1919 
service flew nearly every day within Germany (flights to Stockholm were also 
made), thereby successfully encountering a variety of weather conditions as 
the war had resulted in a huge expansion of severe weather experience. The 
1928 to 1937 period of service included intercontinental and transoceanic flights 
of both the Hindenburg and Graf Zeppelin under a variety of weather and climatic 
conditions. The only injury or death occurred aboard the Hindenburg, which 
would have been avoided had helium been available to the Zeppelin Company. 

During World War I, not one zeppelin-type rigid airship was lost due to a 

structural failure in flight (Reference 15). Included in this statistic were 115 

German Army and Navy airships flying approximately 26, 000 hours, a distance 
9 

of nearly 2 X 10 m (1, 250, 000 mi) during nearly 5000 flights (Reference 15). 
Such statistics, for flights necessarily undertaken under risky conditions, were 
a monumental testimony to the Zeppelin design and operational expertise. 


- 88 - 



Of the 115 zeppelin -type rigid airships utilized in World War I, the follow- 
ing summarizes their disposition: 


Disposition Number 


Dismantled after successful career 2 1 

Surrendered to Allied governments 10 

Destroyed deliberately by own crews 

after Armistice 7 

Shot down by enemy 36 

Landed in neutral or enemy territory 7 

Destroyed by enemy action in hangars 8 

Destroyed by fire in hangar 5 

Destroyed by handling while on ground 6 

Destroyed while landing 12 

Destroyed by fire in air 1 

Destroyed due to defective gas cells 1 

Destroyed due to defective ventilation 1 


In summary, about 33 percent of the 115 ships were retired intact after 
successful careers; 44 percent were lost due to war and war-related incidents; 

21 percent of the airships were lost due to inexperience; less than 2 percent were 
lost due to engineering inexperience (Reference 15). 

This summary suggests that the zeppelin airship design was indeed struc- 
turally reliable. A significant number of airships were lost due to operating 
inexperience. These losses reportedly were due to the war effort, which re- 
duced the time necessary to properly train pilots, flight crews, and ground 
crews. This statement appears to be amply verified by the very successful 
commercial service established by the German Zeppelin Company following 
the war (1919 and 1928 to 1937). During both periods, no losses occurred due 
to operational experience. 

In summary, with respect to the zeppelin airship and airship operations, 
there is nothing inherent in the zeppelin design that would suggest airships are 
inherently unsafe or impossible to operate safely. On the contrary, the 


- 89 - 



zeppelin ships and operations are the premier example of the safety record 
attainable with well-designed airships and properly trained personnel, 

British losses included the loss of their first rigid, the Mayfly, due to a 
ground handling mistake (Reference 15). The R-33 and R-34 experienced good 
success, but the R-38 was lost on its fourth flight. Structural weakness devel- 
oped on the first three flights, after which the ship was repaired and presum- 
ably strengthened. On the fourth flight, maneuvers with the rudders terminated 
in structural failure. The loss was ultimately concluded to have resulted from 
structural weakness brought about by the attempt to design the airship for a 
25, 000-ft ceiling (Reference 15). 

Neither the British 100 or 101 were successful airships, with more than 
one source reporting mismanagement at various levels of these programs. 

The Durand Report (Reference 3) details certain aspects of the design that in- 
dicate technical problems seemingly not typical of well-disciplined programs. 
The Durand Report (Reference 3) details the loss of the R-101, which used 
stainless steel as the principal structural member, as being due to an attempt 
to further increase lift (after the ship had been lengthened to provide added lift 
following its first trial flights). The second attempt entailed a loosening of the 
gas cell wiring in order to attain an increase in gas volume, which permitted 
chafing and subsequent damage of the gas cells, with loss of the ship resulting. 
The R-101 was lost on the first flight after the wires were loosened. 

It would appear that portions of the British experience alone would not lend 
credence to the theme that airships were safe vehicles. It further appears that 
the British losses, which were readily explainable, would have been avoided 
had proper expertise been available to them or perhaps had the expertise been 
better utilized that was available to them. 

American losses relative to the rigid airship include the Shenandoah, 
which was lost in a severe thunderstorm over Ohio. During this storm, 
the airship literally broke in half, thereby indicating a weakness in 

the hull structure in the longitudinal directions. Substantial efforts were sub- 
sequently undertaken to determine a more appropriate longitudinal strength 
criteria for subsequent designs. Later airships, including the Graf Zeppelin, 
Akron, Macon, the British R-100 and 101, and the Hindenburg, incorporated 


- 90 - 



much stronger hulls as a result of the investigative efforts following the loss of 
the Shenandoah. Extensive investigations were conducted following the loss of 
the Akron and Macon, which indicate further increases in hull strength of the 
Akron, Macon, and Hindenburg were desirable. 

The Akron had a very successful 19-month career. It flew about 1700 
hours prior to its loss in April 1933 in a thunderstorm over the Atlantic. The 
airship flew too close to the water for conditions that existed. When a violent 
down gust forced the airship toward the ocean, there was insufficient altitude 
to permit maneuvering. Appropriate instrumentation was aboard the airship 
to permit its altitude to be determined, but was not used. The Naval Court 
of Inquiry and a Congressional Committee of Inquiry made exhaustive investi- 
gations of the loss and came to the conclusion that the loss was due to faulty 
judgment. The airship was found to have been well-built and equipped. After 
its own investigation, the Joint Committee of Congress recommended "con- 
tinuity in experience, training and transmission of knowledge", and stated that 
the experience of Dr. Eckener and other German navigators seems to show 
that airships can be developed to a point where the airship either may avoid or 
survive storms. It was concluded that there is no substitute for knowledge and 
experience. 

The Macon was lost after a successful 22 -month career. It flew about 
1800 hours prior to its loss in February 1935. The Macon was lost due to a 
known structural weakness in the fin support structure. Recommendations to 
repair and materials, etc. , necessary to effect the repair had been provided. 
At the time of the failure, three of the four fin supports had been strengthened; 
however, time did not permit the fourth fin support to be repaired and the air- 
ship was sent out to participate in fleet exercises. It was the unstrengthened 
fourth fin that failed while the airship passed through a gusty Pacific front. 

In 1936, the Durand Committee, which was appointed by Executive Order 
No. 6238 and contained such noted scientists as Theodor Von Karman and 
Stephen Timoshenko, concluded with respect to the general question of air- 
ship safety and future of the airship as an agency of transport. 


- 91 - 



1 . 


All development of a new form of transport and more 
broadly all new developments are subject to possible 
hazards. This has been true in marked degree with the 
airplane, the heavier -than-air form of air transport. 

These hazards and casualties are a part of the price that 
must be paid for all such steps forward. 

2. Study of the record of these casualties leads to the belief 
that, with the lessons that have been drawn from them, 
and with the general advance in our understanding of the 
technical problems of airship design, construction, and 
operation, the probability of a repetition of such casual- 
ties under like conditions should, for future construction, 
be reduced to a point which, if not vanishing entirely, 
may be considered as acceptable in comparison with the 
promise of useful service. 

This committee also recommended that continuing investigations be made 
related to a large airship design. 

With regard to comparative safety statistics with airplanes of a compar- 
able era. Figure 21 has been prepared exemplifying the first of the Durand 
Committee findings. As is indicated in the figure, the airship operations were 
as favorable as, if not better than, airplanes in terms of hours between fatal 
accidents for a corresponding period in time. Airplanes have improved tre- 
mendously since 1939 so that major jet airline typical safety statistics indicate 
more than 1, 000, 000 hours between fatal accidents. 

Given the tremendous improvement that nearly 40 years of technology has 
brought in airplane safety, realizing the outstanding safety record that the only 
real commercial airship operation actually had (even with the exclusive use of 
hydrogen), and considering the findings of the Durand Committee, it seems 
illogical to come to any conclusion other than the safety of an MAV can be 
assured. 


- 92 . 



HOURS FLOWN PER FATAL ACCIDENTS 


100, 000 
8 
6 

4 

2 

10, 000 
8 
6 

4 
2 

1000 
8 
6 

4 

2 

100 
8 
6 

4 

2 

1 


Figure 21 - Safety Statistics for Airships and Airplanes 

- 93 - 




In terms of non-rigid airship safety, the U.S. Navy's experience during 
World War II during which 55, 900 operational flights were made and 550, 000 
flight hours recorded with only one airship lost due to enemy action and loss 
of one crewman essentially speaks for itself. The loss of one of the Navy's 
four ZPG-3W blimps in I960, during which 18 lives were lost, was ultimately 
determined to have been the result of operational error. 

During the entire period of Goodyear commercial (advertising) airship 
operations dating back to the middle 1920’s, not a single passenger injury has 
occurred. During this nearly 50 years of operation, 750, 000 passengers have 
been carried and a distance of nearly 1. 13 X 10* U m (7, 000, 000 mi) flown. 

CRITICAL DESIGN AND OPERATIONAL CHARACTERISTICS 


General 

Rigid airship design had progressed to a rather advanced level in the Ger- 
man Zeppelin Company by 1924. At that point, about 120 rigid airships had 
been systematically designed, built, and operated over a variety of atmospheric 
conditions without a single airship lost due to a storm. At that time Dr. Karl 
Arnstein, who as chief engineer of Luftschiffbau Zeppelin was fully responsible 
for the structure of Zeppelin airships LZ-38 through LZ-126 (the Los Angeles), 
left Germany and came to the Goodyear with 12 of his technical experts. Dr. 
Arnstein continued to serve as a consultant to both the German Government and 
the German Zeppelin Company on the Graf Zeppelin (LZ-127), the Hindenburg 
(LZ-129), and the Graf Zeppelin II (LZ-130). 

This team, along with the invaluable help of Dr. Hugo Eckener of L-Z, re- 
garded as the most knowledgeable expert relative to airship operations in the 
world, provided the Navy with the rigid airships Akron and Macon. Although 
the Akron was lost due to an operational error and the Macon due to a known 
structural weakness (for which hardware to remedy the weakness had been 
provided and partly installed), it was determined following these losses that 


- 94 - 



additional research was advisable. These efforts* lead to greatly enhanced 
methods for determining the static and dynamic loads acting on the airship and 
how these loads collectively lead to the various stresses present within the 
airship. Improved designs of various structural members within the airship 
naturally followed. Since these developments are not generally known, it may 
be of interest to review them. 

An engineering analysis of any structure requires first a breakdown of all 
the loads acting on the structure. Figure 22 shows the breakdown into the 
general classifications of static, aerodynamic, and other dynamic loads acting 
on the airship. The static load group consists of all dead weights, useful loads, 
and the lift of gas. The aerodynamic and dynamic loads either are caused by 
maneuvers involving changes in pressure distribution on the hull and empen- 
nage or by a gust. An airship often encounters gusts when a maneuver 
is being executed; accordingly, this condition must be assumed in the design. 

The top illustration in Figure 22 indicates the combined aerodynamic load- 
ings in straight flight, pitched flight, and passage through a gust. Points on 
Curves A, B, and C represent transverse forces resulting from pressures on 
the transverse sections integrated over the airships length. Lightly shaded 
areas represent negative pressures or suction, while the darker areas indicate 
positive pressures. Curve A results from straight flight; B results from the 
dynamic lift effect in pitched, heavy, or light flights; and C results from 
gusts. The second group of illustrations shows typical transverse sections 
with distributions of the aerodynamic loads at various stations. The curves 
are of a qualitative nature only. 

In the third illustration, Curve A shows the total normal force distribution 
in pitched flight and gives the resultant of the components of all aerodynamic 
loads at stations along the ship's axis. Curve B shows the shear force load 
integrated from the normal forces, and C is the bending moment integrated 
from the shear curve. Curve D represents the maxima aerodynamic and dyn- 
amic bending moments due to maneuvers and gusts for which airship hulls 
would be stressed today. The dots are test values determined by an ingenious 

“ ■“* “ “ 

Performed after Hindenburg was built. 


- 95 - 



A- AERODYNAMIC FORCES DUE TO 
STRAIGHT FLIGHT 
B- AERODYNAMIC FORCES DUE TO 
PITCHED FLIGHT 

C- AERODYNAMIC FORCES DUE TO GUST 
D- AEROSTATIC LIFT 
E- DEAD WEIGHT, USEFUL LOAD, AND 
INERTIA FORCES 
F- POWERPLANT FORCES 



AERODYNAMIC SHEAR FORCES AND BENDING MOMENTS 

A- TYPICAL NORMAL FORCE DISTRIBUTION IN PITCHED FLIGHT 
B- TYPICAL AERODYNAMIC SHEAR FORCES IN PITCHED FLIGHT 
C- TYPICAL AERODYNAMIC BENDING MOMENTS IN PITCHED FLIGHT 
D- BENDING MOMENTS FOR GUST AND MANEUVERS 
fc WATER MODEL TEST POINTS FOR GUST AND MANEUVERS 



STATIC SHEAR FORCES AND BENDING MOMENTS 


SHIP IN STATIC EQUILIBRIUM FULLY INFLATED AND FULLY LOADED 

A- TYPICAL SHEAR FORCES 
B- TYPICAL BENDING MOMENTS 

C- TYPICAL BENDING MOMENTS DUE TO GAS PRESSURE GRADIENT 

SHIP WITH A DEFLATED CELL 

D- TYPICAL SHEAR FORCES 
E- TYPICAL BENDING MOMENTS 



Figure 22 - General Distribution of Forces on Airship 


96 



investigation, financed by a special research grant that the Bureau of Aeronau- 
tics made to the Guggenheim Airship Institute. These tests are discussed sub- 
sequently . 

The bottom illustration of Figure LL shows shear and bending moment re- 
sulting from the analysis of the various static loads. In one condition, all gas 
cells of the ship are fully inflated; this is covered by Curves A, B, and C. A 
is the shear force curve, B is the bending moment curve, and C is an addi- 
tional moment caused by the gas pressure gradient. 

Another condition is the case of a deflated cell, indicated by Curves D and 
E, where the shear force curve instead of being smooth now has a sudden dis- 
continuity. The loss of gas in a cell causes this disturbance in the shear force 
distribution and a slight increase in the maximum static bending moment, 
which must be accounted for. 

The years of regular rigid airship flight operation furnished a fair esti- 
mate as to the magnitude of loads that must form a basis for design criteria. 
More coordinated information came from well-executed flight tests with proper 
instrumentation. For example, valuable flight load data were obtained by 
NACA from the Los Angeles. This method is limited in that aerodynamic dis- 
turbances cannot be controlled and a considerable number of tests under all 
conditions are necessary to reasonably extrapolate for the worst design 
conditions. 

For this reason, wind tunnel tests under hypothetical or arbitrarily severe 
conditions (Fuhrman, Goettingen) that measured forces and moments were con- 
ducted, which formed an early (prior to the Akron and Macon) basis for the 
design criteria. 

Gusts produce the most critical of all aerodynamic loads acting on an air- 
ship. It is unfortunate that the Shenandoah had to be lost to give birth to the 
basic theory for gust loads on the hull of airships. A gust theory was worked 
out by engineers of the Bureau of Aeronautics and of Goodyear. Also, an 
elaborate study of atmospheric gust structure was undertaken; these resulted 
in a vast increase in the knowledge of this all-important point. 


- 97 - 



At the time the Macon was designed, conditions upon which the fin loading 
was based were assumed to satisfactorily cover the gust conditions. However, 
during a flight over Texas, extremely turbulent air was encountered and dam- 
age occurred on some structural elements of the main frame supporting the 
forward part of the horizontal fins; this was the first actual flight indication 
that assumed loads on the forward part of the fins resulting from a combination 
of maneuvering and gust loads were not sufficiently high. All wind tunnel tests 
made in various laboratories in Germany and at CIT, MIT, and NACA in this 
country before the design specifications for the Akron and Macon were esta- 
blished did not indicate loadings sufficiently high to support the actual flight 
experience cited. 

However, tests conducted subsequently on the large scale model of the 
Akron at NACA (1932 and 1937) gave a definite indication that larger loads 
might be concentrated in the region of the forward part of the fin. 

It is also necessary to know what effective local angles of attack exist at 
the fins. Some information was obtained from measurements made during 
flights on various airships which indicated angles that were used when the 
specification for the Akron and Macon was written (10 to 12 degrees). It was 
not, however, until the first water channel test was made in 1940 that actual 
effective angles of attack from bow to stern were accurately determined. 

These results indicate the maxima for an assumed ratio of ship speed to 
gust speed. The 10 to 12 degrees assumed as being satisfactory were con- 
firmed for the forward half of the ship only. The angles at the stern were 
found to be as high as 15 degrees. 

Certain test data from older flights and the 1932 NACA tests, appraised 
in the light of the Macon experience during the Texas flight, gave indications 
of the possibility of higher loading requirements. These indications had 
caused Goodyear to recommend reinforcements on the Macon, then still in 
service, and furnish material for installation in this particular region to meet 
a higher load based on this new information. It was very unfortunate for air- 
ships that this reinforcement was not completed before the Macon was maneu- 
vered through a gusty front when it returned from a mission over the Pacific. 
Reinforcements had been carried out on all fin supports except that of the 
upper fin, where failure occurred. 


- 98 - 



After the loss of the Macon, considerable energy was directed along the 
lines of fundamental research for reappraising all aerodynamic loading require 
ments. This work was conducted by the Guggenheim Airship Institute under a 
grant by the Bureau of Aeronautics and resulted in new types of model tests 
involving a whirling arm tunnel, with and without gusts, and a free -flight, self- 
propelled model in a water channel. These studies eventually resulted in a 
comprehensive understanding of the general aerodynamic loads acting on all 
parts of the airship. During the strenuous wartime activity of a large fleet of 
nonrigid airships, no fin structure failure occurred. 

Figure 23 shows a schematic diagram of the Guggenheim water channel. 
The model, consisting of four articulated sections, was constructed of a magne 
sium alloy casting and weighted until it just floated under the water. It was 
started at the left end of channel n A n with a certain forward speed. Entering 
the cross channel, it was struck by the cross -flow representing the gust. The 
structure of this gust could be arbitrarily controlled so that it closely approxi- 
mated any generally accepted type gust. The forces producing the bending 
moments measured by this apparatus were undeniably the closest representa- 
tion of natural conditions that had been developed. 

Once the loads on any structure are established, there remains the prob- 
lem of determining their effect in terms of stresses and to design each member 
to efficiently carry these loads. In early rigid airships, methods for calculat- 
ing stresses in the hull framework were taken from other fields of engineering, 
mostly civil, and applied with as much judgment as experience permitted, but 
many new and novel treatments were devised as the art grew. 

At the time the Akron was designed, methods for treating generally applied 
forces were well established. The effect of local loads, however, still re- 
quired simplifying assumptions, and these assumptions were checked by build- 
ing and testing full-scale joints, segments, or sections of the actual structure. 
In 1933 and 1934, before the loss of the Macon, the need of a more precise 
treatment for determining the stresses in all basic parts of the airship frame- 
work was expressed at Goodyear and work was started along slightly different 
lines from that previously followed. Methods permitting a high degree of 
accuracy in the calculation of stresses in an airship hull were developed. 


-99 



(A) A SUBMERGED FREE-F LOATING, SELF-PROPELLED MODEL IS STARTED IN STILL WATER AND TRAVELS 
THROUGH A REGION OF DISTURBANCE REPRESENTING A GUST. BENDING MOMENTS EXPERIENCED BY THE 
MODEL AND ITS ENTIRE MOTION IN SPACE ARE RECORDED. 



A. -STILL WATER 

B. - GUST CHANNEL 

C. -SCREEN 

D. - WATER PROPELLER 

E. -GUIDE VANES 


<B) TYPE OF GUST IN CHANNEL RELATIVE TO SHIP'S SIZE. 



X .. .. DISTANCE INTO GUST 
L .... LENGTH OF AIRSHIP 


REGION A-A 


Figure 23 - Investigation of Gust Forces by Water Model Tests 


100 



The accuracy of theoretical methods for such calculations were proved by 
a novel method of stress model testing* Under the added stimulation of the 
Bureau of Aeronautics, Goodyear concentrated on stress model work and de- 
vised a new type of structural element. 

After this girder type was developed, a complete airship model 3 ft in 
diameter and 18 ft long and correctly scaled in its principal characteristics 
was built. The model is shown in Figure 24 and is surrounded by a cage of 
steel rings. Loads representing a great variety of conditions that an airship 
experiences were applied to the model by means of tension or compression 
springs between the joints and the steel rings. 

Close agreement was obtained between the new theory developed and test 
results from this model. This ended a long-drawn controversy between many 
international scientists on the question of whether an airship hull should be 
stressed following the bending or shear theory. 

After this complete model was finished, the work was continued by building 
a stress model of a large bay in greater detail. This model was 10 ft in diam- 
eter. The effect of gas pressure loads was explored by inserting gas cells and 
applying internal pressure, and the effect of change in initial tension in the 
brace wires was studied. 

Another fundamental problem that was answered by a bay model test was 
the question of stability or buckling strength of one bay. The test proved close 
agreement with a new theory which was developed for this particular problem. 
Figure 25 shows the close agreement between theory and stress model measure- 
ments in this case. 

Extensive testing efforts were undertaken relative to structural member 
and structural joint fatigue problems with better design techniques resulting. 

It is certainly essential, if realistic weight estimates for a modern airship 
are to be attained, that the impact of the results of these efforts be factored in- 
to the parametric weight equations along with more obvious considerations of 
today 1 s material and propulsion capabilities. 


- 101 - 




THIS FIGURE SHOWS THE GENERAL STRUCTURAL MODEL OF A COMPLETE RIGID AIRSHIP HULL. THE STEEL RINGS 
FURNISH THE BASES FROM WHICH LOADS ARE APPLIED TO THE MODEL. THE MODEL WAS SUBJECTED TO NUMEROUS 
STATIC AND AERODYNAMIC LOADING CONDITIONS. EXTENSIVE READINGS OF STRESSES IN GIRDERS AND WIRES 
AND OF DEFORMATIONS WERE MADE. 


Figure 24 - Structural Model Tests 


- 102 - 



test 

number 

MOP€L 

IhtrEQHAL 

PRESSURE 

Pc Ttsr 

(#/*H CIUC) 

ft CMcmfcp 

(*/lH elite) 

% 

owenfm 

W Tesr 

Cm-/ ) 

fj CALCULATED 

Cm-' y 

X 

X 

25 mm - HzO 

207 

2/0 

-l/z 

A- 

3.9 

2 

X 

o 

1 73 

ns 

-1 

A 

3.7 

3 

JL 

15mm. HiO 

20-4- 

206 

-/ 

A- 

3.9 

4 - 

jr 

O 

171 

no 


A- 

3.6 

5 

JZC 

25 mm. HzO 

/9<3 

/88.G> 

+A 

3.5 

3.8 

6 

TIL 

o 

tst 

/A8.7 

+ //x 

35 

3.6 


-g- u UNITY FOG TH/S PAGT/CL/LAQ TYPE OF LOAD/NG AND 
TH/S GEA/E&AL TYPE OF ST&L/CW&E. 


(A) TEST DATA OBTAINED ON MASTER BAY MODEL WITH ANALYSIS 



(B) STRUCTURAL MODEL OF AN EMPENNAGE MAIN FRAME. LOADS WERE APPLIED FROM THE 
HEAVY STEEL RING 


Figure Z5 - Comparison of Theoretical Calculations with Test Results 


103 



Maximum Bending Moment Criterion 


Perhaps the most important and most elusive criterion to parametrically 
establish is the maximum aerodynamic bending moment resulting from gust 
loads. Historical criteria are extremely limited in terms of a representative 
fineness ratio range while promising analytical approaches are characteristi- 
cally complex and time consuming. The following paragraphs briefly describe 
the historical criteria and discuss the rationale leading to the development of 
the maximum aerodynamic bending moment to be used in the current para- 
metric study. 

Prior to the mid- 1940' s, the maximum aerodynamic bending moments used 
in the analysis of nonrigid airship envelopes have been estimated from the ex- 
pression 


M = 0.018qV 2//3 L 

This criterion is uniquely related to similarities in mass distribution and 
geometry as well as to a specific gust velocity ratio. Since all nonrigids de- 
signed to this criterion closely satisfied the implied similarities and flew at 
approximately the same speeds, the limits of applicability were not violated. 
Furthermore, considering the corresponding long records of successful flight 
operation, the magnitude of the coefficient is not debated here. However, the 
indiscriminant application of this historical expression to new geometries and 
speeds that depart from its empirical base may well lead to erroneous con- 
clusions. 

In 1944, C. O. Burgess (Reference 18) evolved a criterion for the maximum 
bending moment experienced by a rigid airship encountering a discrete gust 
disturbance having an amplitude of 10.67 m/s (35 ft /sec): 

M = 0. 96 pv V L°* 27 

This expression stemmed from interpretations of a series of related 
studies conducted by the Daniel Guggenheim Airship Institute. These studies 
included water channel, wind tunnel, and whirling arm tests on airship models 


- 104 - 



and an atmospheric gust investigation. Results up to 1940 are summarized in 
Reference 18 with further detail provided in References 19 to 21. 

The principal water channel test article was a small ( 1 / 1 5 0 scale) free- 
floating model of the Akron, which satisfied the dynamic similarity require- 
ment about all three axes. The water gust channel is as described previously 
and is further detailed in Reference 23. Tests were conducted with five differ- 
ent types of fins at various rudder settings and movements, the latter while the 
bow of the ship was entering the gust. The gust profile was characterized by a 
gradient distance of one-half the ship's length (121.92 m, or 400 ft full scale) 
followed by an essentially steady region at the peak transverse velocity, u^ 

(this gradient distance of one -half the airship's length was selected as that 
which would produce the critical loading). 

The commendable analysis of Reference 24, which introduced a full-cycle 
1 -cosine gust profile, tends to support the water channel results illustrated in 
Reference 24. Bending moments were measured at four stations along the air- 
ship^ longitudinal axis during model runs made at velocity ratios (v /u ) of 
2.4, 2.6, 3.5, and 5.25. 

The resulting envelope of maximum bending moment coefficients showed the 
peak occurring at approximately 0.40 L from the stern and a velocity ratio of 
approximately 3. 5, with little change resulting from further increases in the 
incremental angle of attack, u/v. The lower (u/v) data point(s), however, in- 
dicated a substantially linear variation in maximum bending moment over the 
velocity ratio range of principal interest. 

In deriving the maximum bending criterion, Burgess: 

1 . 


2 . 

3 . 


Accepts the maximum bending moment coefficient given 
by the water tunnel test for the Akron 
moment 


(C 


m 


qV 


= 0. 095 at u/v = 1/3. 5) 


Reasonably assumes a linear variation of C with u/v 
7 m 

Simulates the gust profile (indicated by the gust investi- 
gation) with an expression in which the gust velocity 
varies as the width of the transition zone (one-half ship's 
length) to the 0. 27th power; u = u = (L/l )®* ^7 

O ' o 7 • 


- 105 - 



At this point, Burgess departs from nondimensional form and introduces 
a "standard" ship's length, L^, of 243.84 m (800 ft) and a related "standard" 
gust velocity, u^, of 10.67 m/s (35 ft/sec). In effect, he writes: 

u = 0. 198 u Q (L/2)^*^ 

Thus, the maximum effective gust velocity is made a function of the ship's 
length and is not fully developed for lengths under 243.84 m (800 ft). 

Expressing the maximum bending moment coefficient as 


where 


M 

C 

m 


= C 

m 


q V 



2 


V = displacement volume 
Then /C m \ 

M <f> < v > < V) 

in which 

C 

^ = (0.095) (3.5) 

u = 0. 198 u q (L/2) 0 * 27 
u q = 10.67 m/s (35 ft/sec) 
Making the indicated substitutions, 

M = 0. 96 pv V L 0 ' 27 


As evolved, this expression was considered generally confined to hull con- 
figurations dimensionally similar to the Akron and Macon. 


-106 



Having deemed the applicability of historical bending moment criteria too 
limited for parametric usage and confronted with the problem of finding an 
early viable solution, the following assumptions were made: 

!• Differences in maximum bending moment attributable 

to variances in configuration-to-configuration weight dis- 
tributions will not alter the results to any significant 
degree. 

2. Aerodynamic bending moments resulting from penetra- 
tion of a discrete gust disturbance similar to that simu- 
lated in the water tank tests are reasonably indicative of 
critical loadings. 

3. The peak bending moment coefficient obtained in the water 
tank tests is a firm anchor point about which to hinge the 
parametric estimates. 

With the introduction of the foregoing assumptions, estimates of the rela- 
tive change in bending moment coefficient due to changes in fineness ratio, f , 
from the reference point (f = 5.91) were considerably simplified. First, hull 
geometries were described at a fixed volume and varying fineness ratio by 
reasonably assuming similar nondimensional x-y coordinates at a constant 
prismatic coefficient. The related changes in transverse aerodynamic force 
distributions were then estimated using modified (viscous correction) slender 
body theory including an empirical adjustment based on limited experimental 
data for a fineness ratio forebody. The proportional change in the maximum 
bending moment coefficient thus resulting was then applied about the reference 
point to yield the variance shown in Figure 26. Several interesting but prob- 
ably fortuitous aspects of Figure 26 were subsequently noted and are described 
below. 

As fineness ratio is varied at constant volume and prismatic coefficient 
(as in the present study), it can be readily shown that 



- 107 - 




FINENESS RATIO, It d 


Figure 26 - Estimated Variation of Peak Bending Moment 
Coefficient with Fineness Ratio, 


C 

m 


M/q V 


which also closely approximates the actual rigid/non-rigid relationship as 
might be expected. Using this to convert the bending moment coefficients of 

2 /3 ffrn 

Figure 26 from a volume to a V ' L, basis indicates that' 





so refer- 


ax 


enced is nearly a constant and equal to 0. 0822 per radian. The latter com- 
pares closely to 0. 0805 for a 4. 5 to 1 fineness ratio for the semi-rigid airship. 

Another relevant comparison is provided by translating the historical non- 

2 /3 

rigid criterion of C m = 0. 018 (based on V ' L ) to an equivalent gust velocity 
using the present preliminary result: 


u = 0. 018 = 0. 2 19 

v 0. 0822 


which for the 36 m/s (70-knot) class non-rigids equates to a design gust velocity 
of about 7.92 m/s (26 ft/sec) and indicates a comparative degree of optimism. 


- 108 - 




The relative longitudinal bending strengths of prior rigid airships are 
shown in Figure 2 7. where the recommended moment from the water channel 
results have been used to nondimensionalize the ordinate. Of these ships, only 
the Shenandoah was lost due to a longitudinal structural failure and this failure 
occurred in what was reported to be a very severe thunderstorm. 

As can be seen from the figure, the Shenandoah is by far the most inade- 
quate from the standpoint of the findings of the late 1930's and early 1940's. 
Realizing this and that the design represented by the parametric formulations 
for the structural weight of the conventional rigid is about 25 percent stronger 
in longitudinal bending than the strongest airship ever built (Akron and Macon), 
it is believed that the parametric design is structurally very adequate. 

Prior to actually building a rigid MAV, extensive testing and analyses 
will be required to precisely define the aerodynamic loads associated with 
the particular vehicle shape and aerodynamic environment of interest. 
Recommendations relative to this and other technology needs as well as 
suggested approaches for meeting these needs are important aspects of 
Phase II. 


Operational Aspects of Airships 
Mooring and Ground Handling 

From the early 1900's to the mid-1930's, much progress was realized 
in mooring and ground handling large rigid airships. The following paragraphs 
provide a very quick historical picture with respect to the evolution of mooring 
and ground handling techniques and equipment during these periods of time. 

From 1900 to 1909, the rigid airships of the German Zeppelin Company 
were operated from Lake Constance (Bodensee). The airships were docked 
in floating hangars while they rested on floats themselves. * The airships 
were removed from the hanger while still on the floats under the motive 
power of small tug boats. The early airships ascended from and landed on 
the floats. After landing, the airship was replaced in the hangar again under 
the motive force of the tugs. Water landings and ascension were discontinued 

sjc 

Early German Zeppelins also were constructed in floating sheds. 


- 109 - 




A - SUGGESTED AERODYNAMIC BENDING MOMENTS DUE TO GUST AND 
MANEUVERS. AND GROUND HANDLING 

B COMPARATIVE BENDING STRENGTH 01 AKRON-MACON 

L 'OMPARATIVE BENDING STRENGTH Of HINDENBURG 

APPROXIMATE COMPARAUVE MAXIMUM BENDING STRENGTH Of 
GRAF ZEPPELIN 


APPROXIMATE COMPARATIVE MAXIMUM BENDING -.TRFNGIh OE 
IIP ANGELFS 


1 APPROXIMATE COMPARATIVE MAXIMUM BENDING STRENGTH OE 
HENANDOAH 

0 WATfP MODEL TEST POINTS. 


Figure Z7 - Comparative Aerodynamic Bending Strength of 

Different Airships 


on a regular basis in 1909; however, they have been accomplished periodically 
throughout the history of airship operations. This also includes some rather 
extensive and successful efforts with non-rigids. 

From the end of water operations until early 1911, the airships were 
docked and undocked ty manpower alone. In May 1911, however, one of the 
Delag commercial service ships (LZ-8) was carried away by a strong wind 
(cross hangar) from a ground crew of approximately 300 during an undocking 
maneuver. Following this incident, which was a severe blow to the newly 
founded service, Dr. Eckener developed a successful system of docking rails 
and trolleys. In general, the rail system (similar to a train) extended the 
length of the hangar and several hundred feet beyond so that the airship was 


110 - 



well clear of the hangar when it ascended. After the airship cleared the 
hangar, the lines securing the airship to the trolley were loosened and manned 
by the ground crew; the airship then ascended. A similar procedure was 
followed when docking. 

Very large ground crews were used by the Germans to handle the large 
zeppelin warships(600 to 700 men were not uncommon during severe weather). 
The zeppelin warships were never moored during the war ( i. e , they were always 
placed in the hangar after a flight); one reason for this was a noticeable sav- 
ings in weight when the mooring equipment was eliminated, as well as a general 
reduction in hull strength. Designing the hull to withstand mooring loads would 
have induced added weight, which would not have been conducive to attaining 
sufficient bombing altitude to avoid improving defenses. 

Great Britain contributed significantly to developing a suitable technique 
for mooring large rigid airships during nonflight periods so the hangaring 
(docking) requirement after each flight could be avoided. The British developed 
and successfully used the high-mast mooring system. Later in 1919 when the 
British perfected the technique of actually flying to the mooring mast, they 
were able to moor their ships with a ground crew of approximately six men. 
Takeoffs from the high-mast were performed with even fewer ground crew 
members . 

The U.S. Navy later used the high-mast mooring technique on its early 
rigid airships but later developed a preferrable low-mast technique. The 
principal disadvantages of the high mast were excessive cost, permanent in- 
stallation, and a substantial portion of the crew had to remain aboard at all 
times since the airship had to be essentially flown while on the high mast. 

In 1927, the Los Angeles was the first rigid to use a low mast for mooring. 
In addition to being much less expensive, the low mast permitted the airship to 
be unattended while moored when the airship was ballasted heavy. Initial low 
masts used by the Los Angeles were fixed, and a taxi wheel carriage was se- 
cured to the aft car; thus, the airship was able to weathervane, with ballasting 
preventing the airship from kiting in the wind. Less than a year later, a "ride- 
out” car was introduced that consisted basically of a railroad flatcar (free 
to move on a circular railroad track with a radius of about 134. 11 m (440 ft) 


- 111 - 



to which the aft car was secured. The rideout car incorporated rail clamps as 
well as ballasting provisions; thus, the airship was positively secured. Yaw 
cars were used on each side of the rideout car and on the same track as the 
rideout car. Lines from the airship to the yaw cars controlled the lateral 
motion of the airship during mooring. The airship nose was controlled by the 
main mooring line. All line lengths during mooring were controlled from 
winches at the mast, with the airship ultimately pulled to the mast under the 
action of these lines. Once at the mast and with the nose of the airship secured 
into the mast cup, the aft power car was secured to the rideout car. 

The Navy made further improvements by developing a mobile low mast in 
1929, which as a result of its telescoping nature could accommodate the Los 
Angeles as well as the larger Akron and Macon soon to be available. The Los 
Angeles made both flying moors and takeoffs from the mobile mast. In addi- 
tion, the Los Angeles also was docked in the Lakehurst hangar by a mobile mast 
towed by a tractor -type vehicle. This operation required about 60 men, where- 
as 400 to 500 men were required in moderate winds on each side of the airship 
just a few years earlier. 

Further advances in ground handling equipment were associated with the 
Akron and Macon projects. Mobile railroad masts were used, the rideout and 
yaw cars (as in the Los Angeles) were used on a necessarily larger circle, and 
a stern beam was added (which operated on the same railroad track as the 
mobile mast) to control the tails during docking and undocking. In general, the 
handling of these large ships was quite mechanized with the dangers to the air- 
ship and ground crew that had existed a few years earlier greatly minimized 
if not essentially eliminated. 

Very significant improvements were realized by the Navy in handling air- 
ships subsequent to the mid- 1930's. These improvements related to the non- 
rigid airship. However, the equipment and experience gained by the Navy that 
culminated in its handling and mooring techniques for the ZPG-3W airships, 
which were over 134. 11 m (400 ft) in length, are very applicable to much larger 
rigids . The most significant Navy development in this respect were ground hand- 
ling mules and mobile masts. The gound handling mules were highly maneuver- 
able tractors with a constant-tension winch capable of accepting handling line 


- 112 - 



loads from any direction. Landing and mooring of the ZPG-3W required about 
18 to 20 in the ground crew, whereas the early German rigids of a similar size 
often used crews in excess of 400. Docking and undocking were performed with 
11 to 12 men; takeoff required approximately the same number. 

What mooring and ground handling techniques might be used in conjunction 
with an MAV are discussed in the last subsection of this overview. References 
2 5 and Z6 give comprehensive details relative to ground handling and mooring 
of rigid airships and Reference Z7 relative to non-rigid airships. 


W eather 

General - No vehicle is truly an all-weather vehicle in that it can effective- 
ly perform its assigned mission in any weather condition except possibly a sub- 
marine, which can operate below weather effects. However, many vehicles 
can survive severe weather conditions and resume operations after the weather 
has passed. In terms of the severity of weather in which the airship can 
actually operate, the mid- 1950 demonstrations by the Navy and their conclu- 
sions are certainly of interest. 

In 1954, the Office of Naval Research assigned to the Naval Air Develop- 
ment Unit at South Weymouth, Mass. , a project to demonstrate the all-weather 
capability of the airship. Technical guidance and instrumentation were fur- 
nished by the National Advisory Committee for Aeronautics. During the first 
two years, nine flights were made in weather conducive to icing, snow, and 
other winter weather conditions. 

On the last two flights, ice accumulation was recorded, One flight ascended 
and descended through a freezing rain and accumulated an estimated 1361 kg 
(3000 lb) of clear ice. At no time was the control or flight characteristics of 
the airship changed, other than the static heaviness, and the crew became 
psychologically adapted to flying in icing conditions. The airship was a Model 
ZPG-2, with an envelope volume of 27, 612 cu m (975, 000 cu ft), a length of 
104.55m(343 ft), and a maximum diameter of 22.68 m (75.4 ft). 


- 113 - 



As a result of this project, several minor modifications were made in the 
airship used for the experiment, such as adding heading tapes to various valves 
and drains, heat for the pitot head, protective coating for the upper surfaces of 
the lower fins (an X arrangement), flush antennas, electrically heated pro- 
pellers, and ruddevator horn pulley covers. 

The third year's operations consisted of three phases, as follows: 

Phase I - a weekly flight of approximately 30 hours when the 
worst weather was predicted 

Phase II - a joint operation with a squadron from Eakehurst, 

N. J. , to man a specific station for 10 days during 
January when the worst winter weather might be 
expected 

Phase III - a long simulated barrier flight from South Wey- 
mouth over the North Atlantic to another base 
along the eastern seaboard 

During Phase I, seven flights were made, during which icing conditions 
were encounted on two occasions. 

Phase II was scheduled from January 14 to 25, and the worst East Coast 
weather in many years was experienced; icing, fog, sleet, snow, rain, and 
gale winds were encountered. The station was manned continuously for 240 
hours using five airships. Eleven flights were made. The "icing" ship ac- 
counted for five of the flights and on one flight spent 30 hours in icing condi- 
tions. Even though field conditions at South Weymouth were rigorous, the 
operations were conducted off a mobile mast; the airship was hangared only 
once for a regular maintenance check. 

Phase III began on schedule on March 15. After successfully completing 
the assigned mission of a 60-hour patrol across the North Atlantic, the airship 
continued to circumnavigate the Atlantic without refueling. It landed at Key 
West, Fla., after 1 1 days in the air and covered almost 1.34 X 10^ m (8300 mi) 


-114 



The conclusions of the official report on Phase II were: 

"Airship ground handling evolutions can be accomplished in 
virtually all weather conditions, 

"Routine ground maintenance can be accomplished under ex- 
tremely adverse weather conditions. 

"Rime ice accretion at normal airship operating altitudes is 
not considered a deterrent to proper stationkeeping for pro- 
tracted periods of time. 

"Maintaining a continuous barrier station over the Atlantic 
Ocean appears to be feasible under all weather conditions. M 

Wind - Wind is the most important weather element in airship operations. 
However, while high winds in themselves are no threat to the structural safety 
of an airship in flight, historically its limited speed necessitated that high head 
winds be avoided by flying the pressure patterns. This technique has been 
demonstrated in countless instances dating back to the World War I German 
operations . 

Gound operations can be delayed, particularly where the winds are turbu- 
lent. The airship's ability to remain aloft with minimal fuel consumption and 
thereby delay a landing until the unfavorable period passes was a demonstrated 
operational technique. Where the fuel supply was low, the Navy relied on in- 
flight pickup of fuel in containers while the airship was hovering or flying at 
low ground speed. 

Airships can be masted out in winds up to 46. 25 m/s, or 90 knots, [(Reference 
28) and can be docked and undocked in down hangar winds up to 21.03 m/s 
(41 knots). As the wind direction approaches 90 deg to the axis of the hangar, 
the maximum velocity for docking operations approaches 10.28 m/s (20 knots). 

Thunderstorms are typically avoided; however, experienced pilots have 
shown during hundreds of flights in thunderstorms that properly designed 
airships can safely fly in this environment. Modern weather forecasting, 
communications, and constant weather updates along with onboard radar would 
ensure an airship's being able to avoid a thunderstorm. Goodyear advertising 
airships use onboard radar for such purposes. 


- 115 - 



Snow - Perhaps the most troublesome situation for a moored airship is 
when a heavy, wet snow of several inches accumulates on the hull and fin top- 
sides. In several instances, the Navy has flushed the snow off with a fire hose. 
Some promising experiments have been conducted in which the envelope helium 
was heated to melt the topside snow, but the Navy did not think it necessary to 
make this operational. Wet snow usually occurs near the ground and can be 
avoided in flight by a moderate increase in altitude. 

Lightning - Lightning has never caused concern with a helium -inflated 
airship. Although all aircraft attempt to avoid lightning areas because of the 
turbulence that usually exists, there has been evidence of strikes on airship 
cars, fins, and topside radomes but none that caused detectable damage to an 
envelope of a non-rigid. There have been reports of small holes in the outer 
coverings of rigid airships where charges hit the metal structure beneath, but 
the structure was not damaged. 

World War II Record - The most convincing demonstration of the all- 
weather capability of airships took place during U.S. Navy operations in World 
War II when airships patrolled nearly 7. 77 X 10^ sq m (3,000, 000 sq mi) over 
the Atlantic, Pacific, and Mediterranean. Only two bases outside the United 
States had hangar facilities. A significant factor in this performance was the 
high availability factor. Of the airships assigned to fleet units, 87 percent 
were on the line at all times; that is, they were in operation or in readiness 
for operation, which was a high factor for military aircraft during the war. 


STATE OF THE ART 
Rigid Airships (Materials) 

General 

Table 25 presents the state of the art of past rigids with respect to 
materials and material strengths as characterized by the airship Macon. The 
table also includes suggested replacement materials and their properties for 


- 116 - 






attaining a modernized conventional airship. 

The analysis in this subsection is very much a first-order approximation 
and is for illustrative purposes only. A modern airship would not be designed 
on strictly a materials substitution basis. The bending moment and fin loading 
criteria have changed since the last rigid was built and probably would change 
again based on added research and analysis that unquestionably would be per- 
formed prior to constructing another rigid airship. Goodyear developed im- 
proved girder designs after the Macon that, if no additional development in this 
area took place prior to developing another rigid, would be used in a modern 
airship. Even in view of these qualifications, however, the materials substitu- 
tion approach is a reasonable approach for understanding the impact of today's 
technology. 

Associated with any approach of this nature must be a decision as to what 
development risks and costs are reasonable. The parametric analysis (Volume 
II) shows that the “far reaches of today's technology" do not have to be explored 
to arrive at a conventional rigid configuration far superior to the last rigids . 

In fact, substantially more conservatism has been adopted in the parametrics 
than in the following analysis. The general philosophy used in Volume II was 
"what would be used if one were to start fabrication tomorrow". Thus, the 

criticism that sometimes surrounds a parametric analysis hopefully will be 
avoided. 

The following paragraphs relative to a modern Macon should prove 
informative. 


Hull Structure 

For the main structural members of the rigid airship, composites are an 
interesting and promising replacement for conventional aluminum. ' Similar 
NASA studies for an HTA vehicle have indicated structural weight savings in 
excess of 25 percent. Costs at first might seem a problem; however, such 
materials, when they are actually applied in an airship would be apt to be 

'‘Called duraluminum 


- 118 - 


more competitive than today. Naturally, the difference in composite cost 
per pound versus aluminum tends to be minimized since less pounds of the 
composite are required and since fabrication costs potentially can be reduced. 

At this time, however, the application of these materials either on a wide 
scale or as reinforcement members has not been adequately analyzed. 

Stainless steel has been considered in the airship girder application; in 
fact, girder tests have been performed by Goodyear using stainless steel. 
However, the structural elements resulting are thin by comparison to aluminum 
and lead to buckling problems. Other metals could be considered but offer only 
modest weight savings at added cost. 

The most practical approach at this juncture is to apply a modern fatigue - 
resistant aluminum alloy such as 7075 -T6. 7075 -T6 is commonly used with 

aircraft structures and has a yield approaching twice that used on the Macon. 
However, the Aluminum Company of America has indicated that its X-7050 T76 
alloy is a better fatigue -resistant material and possesses a slightly improved 
compressive yield strength. Appendix C of Volume IV provides a copy of a 
letter (along with additional detail on this alloy) from the Aerospace Industries 
Association of America, Inc. (AIA) in which ALA states that NAVAIR proposes 
to substitute the 7050 alloy for all new weapon system airframe components 
and spare parts currently manufactured from 7075, 7079, 7178, and 2014 

alloys. NAVAIR states that substitution is expected to result in improved 
reliability and lower life cycle costs. 

On the basis of this material substitution, the weight of a compression 
member will be (42, 000/75, 000), ^^or 0. 75 percent of the Macon weight; this 
results in a savings of 3616. 10 kg (7972 lb) in the main frame, 507. 78 kg 
(1119 lb) in the intermediate frames, and 22 12. 66 kg (4878 lb) in the longitudinals . 

The steel bracing wires used in the Macon could be reduced in weight 
by approximately 10 to 12 percent using wire per QQ-W-470b. However, 
a substantially improved weight savings would result from the use of 


The British actually used stainless steel girders in the R-101. While this 
airship generally was regarded as overweight, their is no specific reference 
to the stainless steel contributing to excessive weight. 


- 119 - 


Kevlar, Kevlar is being applied in an ever-increasing number of industrial 
and aerospace applications, with Kevlar 49 having been applied widely in the 
cable and rope area. Antenna and tower guy wires of Kevlar (protected from 
ultraviolet by plastic shielding) also are being successfully used. Protection 
of Kevlar airship bracing would not be required since it is internal to the hull 
covering. End fittings and splices were somewhat of a problem with early 
applications of Kevlar in the rope and cable area due to high modulus, which 
did not permit the various yarns in the cross section to assume equal loading. 
Proper construction of the rope or cable and proper end fittings, however, has 
eliminated these earlier problems. The strengths required for the bracing 
wires range from approximately 108.86 kg (240 lb) minimum to 5216.40 kg 
(11, 500 lb) maximum. This corresponds to approximately four plies of 1500 
denier and 166 plies of 1500 denier, respectively. Thus, there are no minimum 
gage constraints, and efficient constructions are viable in both cases. GAC 
has extensively used Kevlar in a number of aerospace applications in recent 
years, and its parent company (GT&R) is currently using it as a belt material 
for tires . 

The tenacity of the steel used in the wire bracing of the Macon averaged 
approximately 2.54 grams per denier. Kevlar, with a near optimum twist, is 
21 grams per denier. Assuming a more conservative value of 19 grams per 
denier, Kevlar will result in an 85 percent weight reduction. Thus, on the 
basis of this substitution, the resulting weight savings is 3441.92 kg (7588 lb). 

There are areas requiring some effort prior to applying Kevlar for defining 
cyclic and static fatigue characteristics. Some work has been performed in 
this area, and other efforts are underway. Specific recommendations will be 
made in Phase II. 

The outer cover wires constitute 714.42 kg (1575 lb) of the miscellaneous 
hull reinforcement. Kevlar will result in a weight savings of 607. 37 kg (1339 lb). 
It is conservatively assumed that a 10 percent savings in the rest of the 


* 


Basic difference between Kevlar 29 and 49 is one of modulus. Kevlar 29 and 
Kevlar 49 are two high-strength, high-modulus, low-density organic fibers 
introduced in recent years by DuPont. 


- 120 - 



miscellaneous reinforcement structure could be realized, or a savings of 
445.89 kg (983 lb). 

The total hull structure weight savings is then 10,831 kg (23, 879 lb). 


Empennage (Structure) 

As in the hull structure, 7050 -T76 aluminum alloy will permit a 25 per- 
cent savings in the weight of the original Macon empennage structure. Thus, 
a weight savings of 1600. 75 kg (3529 lb) would be realized. 

Gas Cells 

Appendix C of Volume IV summarizes the Macon gas cell data. Two dif- 
ferent fabrics actually were used. However, to simplify the calculations, it 
is assumed that the material to be used in the modern Macon must have a 
strength equal to or greater than the strongest Macon fabric, which was about 
892.91 kg/m (50 lb/in. ) tensile strength (warp and fill). Lightweight, scrim 
reinforced films used in recent years in many aerostatic balloon applications 
appear well suited for this requirement. Such a film would have a weight per 
unit area of about 6. 78 X 10 ^ kg/sq m (2. 0 oz/sq yd) for a strength of 89<L 91 
kg/m (50 lb/in. ). 

Goodyear Aerospace's use of a scrim reinforced film in a hot air balloon 
application in recent years attested to the ability to develop adequate seam 
strengths at elevated temperatures that would encompass the range of strengths 
and temperatures of interest in the gas cell requirement. Other companies 
and government agencies have used scrim reinforced films in a wide variety of 
applications over many years. With scrim reinforcement, the film tear strength 
is greatly increased and damage due to handling during manufacturing and in- 
stallation is definitely minimized. 

Although not expected to be a problem, one area that would require added 
evaluation is the cyclic environment that the gas cell would experience once 
in use within the airship. This would be a rather straightforward program and 



could be performed in a laboratory environment using a scaled gas cell and hull 
structure section. The laboratory pressure and temperature environment 
would be controlled through a predetermined cyclic exposure representative of 
actual flight conditions. The laboratory environment would be cycled, in a 
few weeks maximum, the same number (or greater number if desired) of 
cycles that the cell would see during its total life in an airship. Permeability 
and tensile strength tests would be performed before and after to verify lack of 
degradation. Various film materials could be evaluated and screened in this 
manner. 

The total gas cell area for the Macon was 4. 50 x 10^ sq m (53, 848 sq yd) 
(see Appendix C of Volume IV). For the 6. 78 x 10’ 2 kg/sq m (2. 0 oz/sq yd) 
reinforced film, this results in a total gas cell weight of 3053.18 kg (6731 lb), 
or a savings for the Macon of 6821. 24 kg (15, 038 lb). 


Outer Cover (Doped) Including Empennage 

The outer cover of the Macon was cotton cloth (approximately 1160. 79 kg/m 
(65 Ib/in. ) predoped prior to installation, with the final coats of dope applied 
after installation. The weight of the finished fabric was about 0.456 kg/sq m 
(6.1 oz/sq yd). 

The use of a film laminate for the outer cover of the modernized Macon 
appears to be a very practical consideration. While Kevlar seems to be a 
logical choice, minimum gage* is a problem even with the 200 denier yarn. ** 
Therefore, for the current discussion the use of dacron will be considered. A 
dacron cloth with sufficient strength would be about 0.120 kg/sq m (1.6 oz/sq yd). 
A Tedlar*** film would be used to protect the dacron from ultraviolet radiation 
and conservatively would have a weight-to-area ratio of 0.075 kg/sq m (1.0 oz / 
sq yd). In addition, the film would prevent moisture from penetrating into 

* 

For larger higher-speed conventional airships, minimum gage may not be a 
problem and its use in such a case should be reconsidered. 

200 denier is currently the smallest denier Kevlar yard available. DuPont has 
stated that, at this time, it does not intend to manufacture smaller deniers. 

5j< 

Trademark of J. T. Scheldahl Company. 


- 122 - 


the interstices of the dacron cloth. While adhesive layers as small as 0. 037 kg/ 
sq m (0. 5 oz/sq yd) are possible, 0. 0561 kg/sq m (0. 75 oz/sq yd) is more 
practical as an average production consideration. Thus, the total film lami- 
nate weight -to - area ratio would be about 0.250 kg/sq m (3.35 oz/sq yd) com - 
pared with the 0,456 kg/sq m (6. 1 oz/sq yd) for the Macon outer cover; this 
represents a weight savings of 2579. 1 7 kg (5683 lb). 

Film laminates have found widespread application in balloon applications 
and easily can be adapted. Once the grommets are installed, the film lami- 
nates would be laced to the hull structure just as the predoped cotton outer 
covering actually used on the Macon. Handling during manufacturing and in- 
stallation should not be a problem. As with any new material, a film laminate 
would require an individual or component qualification program prior to its 
acceptance into a modern airship design. 


Gas Valves, Hood, Ventilation; Fuel and Oil System; 
Ballast and Water System; Controls; Mooring and 
Grounding Handling; Miscellaneous 


It is conservatively assumed that each of these weight groups can be re- 
duced by 10 percent of the original Macon weight. 


Netting 

If the original netting is replaced with Kevlar, a total netting weight of 
61.69 kg (136 lb ) will res ult . 

Control Car and Crew Quarters 

The revised weight for these weight groups based on the X-7050 T76 alloy 
is (42, 000/75, 000 ) l / 2 ( 1 7 1 8 + 6450 ), or 2 772. 40 kg (6112 lb). 


- 123 - 



Electrical System; Heating and Ventilating; 
Instruments; Radio and Communication 


The weight of these groups has been increased to the approximate weight 
of these systems in the Boeing 747. 


Power plant 

Modern turboprop engines with gear box result in approximately 0.4 pound 
P®* 1 horsepower uninstalled. Installed weight per horsepower generally is con- 
sidered to require one pound per horsepower. Thus, for the original Macon 
power rating of 4480 horsepower, the powerplant weight was 2032. 13 kg (4480 lb). 


Water Recovery 

Although water recovery cannot be effectively used with the turboprop, 
the weight of this category has been retained under the assumption that an al- 
ternative technique can be provided today at approximately the same weight. 
Appendix H of Volume IV discusses the possibilities of alternative techniques. 

Summary 

In summary, the empty weight-to-gros s weight ratio has been reduced 
from 0.59 to 0.34 by using materials and propulsion characteristics of today's 
technology. 


Material Life Characteristics 

In general, the fabric materials used in the Macon would have remained in 
a serviceable condition from five to seven years. The duraluminum was ex- 
pected to have a life of at least from 10 to 15 years. 


- 124 - 



By way of comparison, an envelope 1 ' of one of the Goodyear advertising 
airships has been in service for more than seven years. Currently, it appears 
that 10 years is a reasonable life time. 

Twenty-year service lives for film and film laminates are considered 
reasonable specifications today and are undoubtedly attainable. Life character- 
istics of materials common to HTA craft and their maintenance requirements 
are not given since they are well known. 

In terms of the Goodyear advertising airships, the only maintenance per- 
haps not somewhat typical of HTA vehicles is when the top of the envelope is 
recoated to ensure continued ultraviolet protection. This requirement would 
probably continue for non-rigids using coated fabrics. It would not be a re- 
quirement for film laminates such as those suggested for a modern rigid. 


Non-rigid Airships (Materials ) 

In general, many of these rigid airship considerations are applicable to 
the non-rigid and thus are not restated. The gains in most cases, however, 
would not be as dramatic since the last non-rigids were designed in the mid- 
1950's. The use of Kevlar in the envelope is one area of significant benefit 
requiring specific comment. 

The use of Kevlar in the envelope for non-rigids of the ZPG-3W size and 
larger offers substantial increase in useful lift at a given gross weight. Kevlar 
has a str ength-to-weight ratio about twice that of dacron. Prior estimates 
have indicated that the useful lift of the ZPG-3W, which used a neoprene coated 
dacron cloth envelope, could be increased 25 percent by a neoprene coated 
Kevlar cloth. Further substantial improvement is attainable via film laminates. 
In the non-rigid, the film renders the envelope impermeable and protects the 
load-carrying member from weathering. Whether film laminates can be in- 
corporated into an LTA application where a man rating is required requires 
considerable additional testing and evaluation. Accordingly, the subject is not 
dealt with further in this phase. The parametric analysis (Volume II), 
s !< 

Neoprene coated dacron. 


- 125 - 


however, illustrates the benefit derived from neoprene coated Kevlar, While 
some unknowns remain, for instance, in the area of static and flexural fatigue, 
through proper choice of the many variables at the designers disposal coated 
Kevlar is a very promising consideration for non-rigid envelopes. Studies 
are underway by a variety of agencies and companies; the results or interim 
results would permit a comprehensive plan to be developed in Phase II that 
would scope the magnitude of a program leading to the demonstration of a 
Kevlar envelope. 

A recent innovation, known as Doweave, may be of interest in terms of 
detailed consideration during Phase II. This material is a three-thread set 
weave in a single ply, and its use would eliminate the conventional "bias” ply 
used in past non-rigids. Both cloth and coating weight would be reduced for 
the same capability. Envelope fabrication costs also would be reduced. Fur- 
ther analysis would possibly reveal whether the reduced fabrication costs would 
offset increased cloth cost that would undoubtedly occur compared with a 
standard weave. 


Rigids (Economically ) 

Past conventional rigids were constructed in a labor intensive manner. 
Hulls were assembled in a single large dock in a continuous fashion frame by 
frame. Frames were individually constructed in an adjacent area and moved 
to the hull assembly area when needed. The wire bracing was terminated by 
hand wrapping and soldering. The time required to terminate one wire brace 
was about 40 minutes, and there were several thousand such terminations in a 
large airship. Today, this operation would be performed by a bench - mounted 
mechanism in about 75 percent of the terminations and by a hand-held mecha- 
nism in 25 percent of the terminations. Such an approach would reduce 
the 40-minute time period to something nearer three minutes. Use of 
Kevlar, instead of steel wire, as a bracing material could foreseeably further 
reduce the time to effect bracing terminations. 

The hull itself would be errected in an entirely different manner than pre- 
viously. Firstly, today's tooling techniques would permit the components 


- 12 6 — 



comprising the longitudinals, main frames, and intermediate frames to be 
final cut prior to assembly as opposed to a cut-to-fit at assembly technique that 
was used to a certain extent previously. Additionally, the time required in 
joining the longitudinals to the main and intermediate frames would be greatly 
reduced. Short sections of the longitudinals would be joined to the main and 
intermediate frames at the time the individual frames are assembled. The 
longitudinals would then be attached during the errection of hull sections to the 
extensions emanating from the frame proper. Thus, the interface would be a 
straightforward simple contour connection as opposed to prior techniques 
where, at erection of the entire hull assembly, the longitudinals were attached 
directly into the frame which required the fitting of complex cuts on the inter- 
facing members. 

The time-consuming attachment of the outer cover would also be minimized 
both by improved technique and the use of a covering not requiring doping after 
installation. 

Perhaps most significant in reducing manufacturing costs would be the 
revision in hull errection. The hulls of rigids of conventional construction 
would be built up in sections with scaffolding used to facilitate access to the 
hull section as construction proceeded vertically upward. At the longitudinal 
center of the hull section would be the main frame with intermediate frames 
(one-half the number per cell) on either side of the main frame. The hull 
sections would then be joined at erection by overhead equipment that would 
attach, by means of cables to the main frame, to each hull section and rotate 
and translate the sections to the desired location. The hull sections could be 
moved more easily than individual frames were moved previously because of 
their greater rigidity. 


-12 7 - 



While assessing the impact of such modifications on acquisition cost is far 
beyond the scope of this phase of the study, it is believed the results in Figure 
28 are of some interest. Figure 28 presents a very preliminary estimate, 
using the historical data presented previously for today's acquisition cost of 
rigid airships of conventional construction over a range of weights of interest 
to this study. Salient features of the estimate are: 

1. The historical average of 13.23 direct construction man-hours 
per kilogram (6. 00 direct construction man-hours per pound) 
of empty weight has been used (thus, prior construction tech- 
niques are implicit) 

2. A lot size of 400 units has been assumed, and conservatively 
an 85 percent learning curve has been applied 

3. 1974 material costs have been used as well as 1974 cost for 
propulsion and avionics 



Figure 28 - Preliminary Estimate of Price versus Empty 
Weight for Conventional Rigid Airships 


- 128 - 




4. Hourly rates (labor and overhead) correspond to 1974, 
those of major domestic airframe manufacturers 

5. Erection facility and maintenance facility costs have been 
amortized. 

6. Tooling costs were assumed to be 4 percent of the average 
factory cost of 400 units 

7. RTD&E costs were considered to be a factor of 10 greater 
than the cost of the first unit 

8. Indirect support was considered at 5 percent of total direct 
support 

9. Spares were considered at 2 percent of total direct plus 
indirect 

10. Profit was considered at 1 0 percent of total cost including 
spares 

From the results of this preliminary analysis, it is apparent that rigid 
airship acquisition costs can be expected to be below that of today’s major do- 
mestic aircraft on a price -per -pound basis. It is plausible to suggest that 
when considering the impact of the prior discussion relative to new construc- 
tion techniques that the price per pound may approach that of light airplanes. 

Non-rigids (Economically) 

A similar analysis could be performed for the historical data provided 
earlier for non-rigids with similar trends resulting. It is not clear, however, 
at this point that another such analysis would add significantly to our under- 
standing. Accordingly, further economic analyses are better reserved for 
Phase II. 


Operational Aspects of Conventional MAY'S 
Mooring and Ground Handling 

Based on the brief historical summary presented earlier, it was apparent 
that much progress had been made in mooring and handling large airships. In 

view of the projected in-frequent requirement to hangar (or dock) of an MAV, 
prior techniques may well be substantially adequate. In any event, quantum 


-129 



advances are not essential in this respect to render an MAV a viable consider- 
ation. 

It is generally acknowledged that the manner in which prior airships were 
moored requires considerable improvement although the Navy work of the 
1950's was approaching what might be regarded as commercially practicable 
operation for the size airship being used. Larger ships, however, would re- 
sult in large crews and added equipment given the same approach. 

In general, an automatic flight control system consisting perhaps of much 
of the equipment in Figure 29 would be on-board a large MAV. This equipment 
would lead to a greatly improved opportunity to minimize ground crews and 
ground handling equipment. With such a control system, under all but the most 
severe of conditions, an MAV probably could be flown to and restrained to (with- 
out external assistance from a ground crew) a turntable that would permit the 
ship to weathervane subsequent to landing. 

After suitable computer simulations are developed to model the behavior 
of an MAV with the control system under a variety of landing environments, the 
ability to provide "pinpoint” controllability is not limited, as suggested above, 
to only the most severe conditions. Given this possibility, such a control sys- 
tem may require some augmentation in terms of ground crew and equipment 
similar to that used by the Navy in the late 1950’s. Although not used in 
past airship operations, it seems reasonable to suggest television as an aid to 
ground handling and perhaps more importantly to mooring. 

Other approaches such as those described in Reference 29 have been sug- 
gested that do not require the actual landing of the airship while cargo is off/on 
loaded. Such a system would have its greatest merit for operation in areas 
where fixed bases do not exist. However, in view of the results of this study 
it is doubtful that the vehicle suggested in Reference 29 is best suited to the 
delivery of cargo to areas other than where fixed bases do not exist. 

Relative to fixed base operations, the suggestion made relative to landing 
and mooring appears more realistic in that it is a much smaller departure 

)•( 

Extremely large MAV's would not be docked for maintenance nor would they 
be built in an enclosed hangar (Reference 29). 


- 130 - 




Figure 29 - Automatic Flight Control System Schematic 

from past practices and would appear to result in less weight penalty to the 
airship itself. 

Depending upon the response of the turntable/airship system to changes in 
the incident winds, it may be desirable to have a network of wind sensors sur- 
rounding (at a suitable distance from) the turntable. Information from the sen- 
sor would provide inputs to a turntable drive mechanism, which in turn would 
orient the MAV into the wind. A similar scheme is suggested in Reference 29. 

Weather 

General - Very significant progress in forecasting general and local 
meteorological conditions has been realized since the last rigid airships were 


- 131 - 

















flown, a factor that has contributed much to the continuing improvement in HTA 
safety. The use of the avionics onboard today’s modern aircraft will be essen- 
tial in an MAV. This capability will provide the ability to avoid severe 
weather, something that the German pilots were able to do very successfully 
even without such equipment. 

Onboard radar in the Goodyear advertising ships is used to avoid severe 
weather when the airship is penetrating passing fronts. 

Not only will the advent of weather satellites, onboard radar, improved 
navigation, and improved communications result in safety benefits but the 
economics of prior operations also will be improved. These capabilities will 
permit an optimal (least unfavorable) headwind route to be flown. The adverse 
effects of headwinds themselves will be minimized by higher design velocities 
that, with today’s extensive advances in propulsion and noticeable improve- 
ments in materials, can be obtained with minimal weight penalty. Neverthe- 
less, avoidance of excessive headwinds will remain an operational considera- 
tion. 

In past operations, it was often common to fly close to the ground (where 
turbulence is less) during very severe weather. Controllability of past config- 
urations in this environment probably was not adequate since, to obtain a nose- 
up attitude, the tail of the ship necessarily was forced toward the ground. 
Vectored thrust can remedy this problem, but a more suitable approach in 
some cases may be to use bow elevators. These devices were successfully 
incorporated and used on a non-rigid airship; thus, their feasibility is not 
questionable. 

Wind - The subject of minimizing the adverse effects of headwinds as well 
as the use of radar to avoid severe weather has been discussed. The techni- 
que that would be used in a conventional MAV relative to landing in extremely 
adverse wind conditions is the same as previously used; this consisted of delay- 
ing the landing until the turbulent ground winds passed. 

Snow - The techniques devised by the Navy relative to this problem and 
discussed earlier should prove adaptable to future operational needs both dur- 
ing flight and while moored. 


- 132 - 



Tropical Storms - There are recorded instances where airships (such as 
the Macon) have survived aspects of tropical storms. It would be essential 
that an MAV (as in HTA vehicles) be removed from areas of expected tropical 
disturbances . 


Institutional Constraints 

Institutional constraints are described in Volume I. Their impact relative 
to the parametrics is addressed in Volume II. 

Current Goodyear airship operations have no reason to operate other than 
in a static equilibrium, or light condition, or in conditions not suited to visual 
landings. As a result, exemption No. 1552 dated 27 March 1972 has been ob- 
tained that permits Goodyear's airships to operate over populated areas within 
the same minimum altitude and VFR weather minimums as helicopters. The 
effect upon flying configurations in a heavy condition will have to be reviewed 
during Phase II to assess the constraints that may be placed on such operations. 

Buoyancy Management 

This subject involves a variety of considerations and is included in Figure 
28. This subject, as related to the increase in buoyancy accompanying the 
consumption of fuel of a density greater than that of air, is discussed in Volume 
II. There are schemes such as those used in the Graf Zeppelin that eliminate 
this problem. The multitude of possibilities available over the range of para- 
meters involved in this phase relative to the approaches for buoyancy manage- 
ment eliminates a serious discussion of refinements or revision to past techniques 
until specific vehicle /mis sion combinations are considered in Phase II. 


Many considerations are involved including type of propulsion system, type 
of fuel, type of vehicle, use of heavy takeoff, whether vehicle is power exten- 
sive, and altitude requirements. Accordingly, many specific decisions, often 
interrelated, must be made unless one is to present a shopping list. While no 
specific design innovations have been included in the "parametric design, " the 
weight equations include allowances for buoyancy management techniques up- 
dated to include today’s materials. 


- 133 - 



Recent LTA/HTA Vehicles and Concepts 

Recent interest in LTA combined with HTA as a hybrid vehicle featuring 
the best of these two has received considerable attention in recent years. 

There are several reasons for this; 

1. A growing awareness of the ecological and energy problems 
associated with current transportation systems 

2. The realization that the operational characteristics and 
capabilities of airships either are not available or are 
available only to a limited extent in other transportation 
systems 

3. The conviction that the quantum advancements in aerospace 
and aviation systems technology can place modern airships 
on the same level of safety, economy, and performance 
capability as alternate transportation system 

4. The identification of many conventional and unique mis - 
sions that modern airship vehicles could potentially per- 
form cost effectively 

As a result of these reasons, conventional and unconventional LTA as well 
as LTA/HTA vehicles have been proposed and analyzed to varying degrees. 

The more notable configurational concepts and designs to emerge in recent 
years are discussed in the following paragraphs. It is beyond the scope of 
this report to critique, evaluate, or rate the concepts/designs. Such a task 
would undoubtedly and understandably be complicated by the varying extent of 
design analyses performed and the extent to which results of analyses that 
have been performed might be considered proprietary and therefore unavail- 
able. It is certainly fair to say, however, that Goodyear maintains an interest 
and knowledge of continuing LTA and LTA/HTA vehicle concepts and designs 
and has applied this awareness and knowledge throught the present study. 

The Airfloat heavy lift transporter by Airfloat Transport Ltd. and a cargo 
transporter by Cargo Airships Ltd. are two of the most notable efforts under- 
taken in recent years by British concerns. The Cargo Airship Ltd. project in- 
volves a 1, 132, 800 cu m (40, 000, 000 cu ft) conventional rigid long-haul airship 
while the Airfloat project considers a 849, 600 cu m (30, 000, 000 cu ft) conven- 
tional rigid designed for short-range carriage of large indivisible loads. 

-134- 



Certain points of interest made in the Airfloat study, some of which have 
been commented on previously, are summarized below: 

1. Possible elimination of water recovery apparatus by 

a. Heavy takeoff with decreasing fuel load accounted for 

by modulating dynamic lift 

b. Heated helium at takeoff, which is permitted to cool 
as fuel is consumed 

c. Intermediate ballast pickup 

2. Loading and unloading cargo while the airship is hovering, 
which necessitates a somewhat elaborate but plausible bal- 
last exchange system, the rudiments of which Airfloat has 
outlined. Airfloat also has realized the requirement for a 
means of sensing and correcting misalignment from wind 
directional changes, etc. , during the hovering (loading and 
unloading) process. Plausible concepts for accomplishing 
this are also suggested. 

3. Use of a turntable permitting the capability of mooring the 
airship over its entire length while still permitting it to 
weathervane. 

With regard to hull construction, the '’conventional rigid" as well as the 
semi-monocoque metalclad and an aluminum faced honeycomb skin were con- 
sidered by Airfloat. The "conventional rigid" using update materials was the 
approach ultimately retained. 

Powerplants considered included nuclear, gas turbine, reciprocating 
diesel, and reciprocating petroleum. Airfloat concluded that nuclear power, 
although attractive for long hauls, was expensive for producing a limited num- 
ber of airships and was not readily available. Gas turbines were ultimately 
favored due to their superior power -to -weight ratio, which more than offset 
their somewhat higher specific fuel consumption. 

Another British effort, the Skyship Project, is apparently continuing with a 13.61 
m (30 ft ) "prototype M having recently flown in Cardington, England. The ope rational 
Skyship configuration isa 1, 047, 840 cu m(37, 000, 000 cu ft ) volume flying sauce r - 
shaped vehi cle some 317.52 m ( 700 ft ) in diameter . Fuel and payload capability 
is on the order of 4 X 10^ kg (400 tons ); maximum speed is 51.44 m /s (100 knots ) . 


- 135 - 



The Heli-Stat (Reference 30) heavy lift vehicle by the Piasecki Aircraft 
Corporation is currently undergoing detailed study and definition by that firm 
under contract to the Navy. Goodyear is assisting Piasecki with such items as 
defining the LTA hull and helicopter support structure, preparing manufactur- 
ing cost information, and providing guidance from the overall LTA aspects of 
such a vehicle . 

This 68, 032 kg (75 ton)payload Heli-Stat uses an essentially conventional he- 
lium-filled rigidairshiphull (minus tail surfaces )of approximately 82, 128 cu m 
(2,900,000 cu ft) to which four CH-54B helicopters are attached. The LTA hull and 
helicopters are joined by a lightweight truss work that ties the fuselage structure of 
the helicopter to the main frame structure of the LTA hull. Thus, the 68, 032 kg 
(75 ton)payload design employs demonstrated technology in the LTA hull and exis- 
ting components in the helicopters to arrive at a vehicle that can lift payloads 10 
times those of one of the helicopters alone and more than twice as much as an 
LTA vehicle of comparable size. The static lift of the LTA structure supports 
approximately the full weight of the entire vehicle; the rotor thrust is available 
for useful load and maneuvering control forces. 

The helicopter's control systems are interconnected so that they respond 
to one set of controls in the master control helicopter. A qualified pilot is 
stationed in each helicopter and serves as a manual instrument-monitoring 
system with override capability if a component fails. 

The helicopters are free to use their cyclic pitch in all directions (approxi- 
mately 11 deg). In addition, they can be made to rotate about a transverse 
axle in longitudinal pitch 60 deg forward and 3 0 deg aft but normally are locked 
in a trim position. In the lateral direction, in addition to the rotor's lateral 
cyclic control of approximately 11 deg, the helicopter can be made to tilt out- 
board approximately 11 deg. 

In the yaw direction, the helicopters are rigidly fixed to the aerostat struc- 
tural keel. For yaw moments, the port and starboard helicopters can differ- 
entially incline! their longitudinal cyclic. For lateral roll control, differen- 
tial rotor collective pitch on one side, versus the opposite side is used. Pitch- 
ing attitude is via differential collective pitch of the forward rotors versus the 
aft. 


- 136 - 



Propulsion is achieved from the forward cyclic pitch of all rotors. The 
helicopters can be included as the dynamic lift of the aerostat develops with 
forward speed. The aerostat angle of attack, and hence its lift, can be inde- 
pendently adjusted by its longitudinal trim elevators. Retardation is achieved 
by tilting the rotors aft. 

Plausible approaches for emergency ( i. e . , complete power loss in one 
helicopter) landing have been advanced in terms of complying with existing 
FAA regulations. Plausible mooring provisions have been proposed and are 
currently being reviewed for possible improvement. 

The Aerocrane is a heavy lift vehicle proposed by the All American En- 
gineering Company. Parametrics have been performed by All American for 
payloads up to 226, 200 kg (250 tons ), with resulting sphere diameters of 76.3 
m (250 ft) and forward velocities up to approximately 24. 7 m/s (48 knots). 

A small 6.8 m (15 ft) in diameter HTA model of the Aerocrane 
concept has been made by All American. While the model does not use a lift - 
ing gas, it illustrates the fundamental vehicular principles involved in the con- 
cept. 

Under contract to the Navy (see Reference 31), Goodyear performed a 
comparative parametric and design study of conventional rigid and nonrigid 
airships as well as dynamic lift aerostats (Dynastat) as applied to future naval 
missions. The Dynastat vehicle is one class of vehicle being considered in 
the current study. * The study considered gross weights ranging from 45, 360 to 
680, 400 kg ( 1 00, 000 to 1 , 500, 000 lb), design velocities ranging from 46.1 m/s 
to 107.9 m/s(90 to 210 knots), static lift- to -gross weight ratios ranging from 0. 6 
to 1 . 0 for the Dynastat- type vehicle s and 0 . 8 to 1 . 0 for the conventional airships , 
and operational altitudes ranging from 457.20 to 6096 m (1500 to 20, 000 ft). 

The Helium Horse also is a configuration involving aerodynamic and aero- 
static lift similar in some respects to the configuration of that description 
analyzed in this study. 


jjc 

Reference 32 discusses a semibuoyant, lifting-body airship that is described 
in Volume II. 


- 137 - 


Another area of study by Goodyear that is of some historical interest rel- 
ative to modern airships is to control the boundary layer. Reference 33 sum- 
marizes the Goodyear boundary layer control (BLC) study, which in this case 
is applied to a non-rigid airship. 

The findings of the BLC airship showed sufficient increase in the airship 
performance to warrant further study. The following specific conclusions were 
offered: 

1. The wind tunnel tests confirm the ability of the theoretical 
methods to predict the boundary layer control of a body of 
revolution at zero angle of attack. 

2. The theory confirmed by the wind tunnel tests together 
with allowance for inlet and duct losses predicts that the 
bare hull power requirements for a full-scale BLC airship 
hull of fineness ratio 3. 0 at zero angle of attack can be 
expected to be 10 to 20 percent less than the power re- 
quirements of a conventional airship hull of equal volume. 

3. The difference in the components, other than the hull as- 
sociated with the two configurations, offer an additional 

5 to 1 0 percent reduction in power requirements for the 
BLC non-rigid airship. 

4. A BLC configuration with a fineness ratio 3. 0 can be ex- 
pected to reduce the total propulsive power requirements 
15 to 25 percent of a conventional non-rigid airship of 
equal volume. 

5. If both configurations have equal fuel quantities available, 

BLC can be expected to increase the endurance 2 0 to 40 
pe rcent. 

6. Indications exist that the fineness ratio of 3. 0 may not be 
optimum for a BLC airship. 

Several recommendations resulting from the BLC study will be integrated 
into an overall LTA technology plan to be developed as a part of Phase II. 

A third area of investigation by Goodyear in recent years applicable to 
the concept of modern airships is that of gimbaled stern propulsion. Under 


- 138 - 



contract to ARPA (Reference 34), Goodyear modified one of its advertising air- 
ships to incorporate a gimbaled stern propulsion system (see Figure 30) and 
subsequently demonstrated the feasibility of this approach for low -speed con- 
trol of the conventional airship configuration. Stern propulsion is often con- 
sidered and logically so for the BLC airship because the stern propeller to an 
extent affects BLC. In the Phase II technology plan development, recommen- 
dations are contemplated regarding the combination of stern propulsion and 
BLC investigations as an area leading to possible worthwhile improvements in 
future airship performance. 

Aereon Corporation has built vehicles and conducted design studies of 
vehicles combining aerostatic and aerodynamic lift as reported in Reference 
35. Aereon III was a three-hulled rigid airship 25.91 m (85 ft) long. This con- 
figuration was dismantled in 196 7, and a vehicle combining aerodynamics and 
aerostatic lift (called Dynair ship ) was subsequently built and successfully flown. 
This configuration could be considered for the aerodynamic /aerostatic vehicle 
analyzed during this study. 

Interest in the Soviet Union relative to LTA and LTA/HTA vehicles in re- 
cent years reportedly has been significant. In 1965, the first all-Soviet Union 
Conference on Dirigible Construction was held, at which time new techniques 
and design criteria were explained. Substantial public controversy relative to 
the desirability of extensive development of dirigibles by the USSR following 
this conference also has been reported. While there is no reported authoriza- 
tion of major national proportions, the Soviet Ministry of Aviation is said to 
have authorized full exploration of several schemes. 

One known project that reached a hardware stage is described below. An 
airship design group in Kiev in 1969 built and tested a cigar-shaped airship 
known as the D-l, which is 84 m (275.6 ft) long and 25 m (82 ft) in diameter. The 
D-l is a double -skinned semi -monocoque construction; the hull liner is fiber- 
glass and the space between the inner and outer walls is filled with foam. The 
airship is fully rigid, with four transverse frames and four stringers installed 
inside the lining. One of the stringers has been reinforced to function as a 
corridor between the cabins, which are located in the bow, tail, and center of 
the ship below the hull. Helium gas bags of a thin synthetic material were 
reportedly used. 


-139 




0/ ^ 






Figure 30 - Goodyear Mayflower Stern Propulsion Demonstration 





The D- 1 reportedly operates at altitudes up to 7000 m (2 2, 92 0 ft) and can 
travel 3000 km (1620 naut mi) nonstop. A turbofan tail-mounted engine is 
reportedly used, with speeds ranging up to 200 km (108 naut mi) per hour. 

Also, a mooring mast with a revolving platform is planned. 

Airship designers in Leningrad reportedly are working on plans for a 
double -hulled rigid airship under the supervision of an ae ro -nautical commis- 
sion sponsored by the Soviet Geological Society. Uses for which airships have 
recently and are apparently still being considered are: 

1. Transporting heavy loads over long distances in Siberia 

2. Transporting and installing heavy structures at building 
sites 

3. Radio communications 

4. Medium-range airbuses and tourist cruisers 

Various reports that non-rigid airships are being used in the Soviet Union 
(apparently since the early 1960's) exist. Designers (W. Schmidt and Ulrich 
Queck) in East Germany are reportedly involved with an advanced airship de- 
sign called the Dolphin. The concept is reported to have originated from a 
study of the mechanism of motion employed by the Dolphin as it propels itself 
through the water. Claims, which perhaps can be substantiated although no de- 
tailed analysis is known to be available, are that such an airship would be able 
to fly at over 500 km (270 naut mi) per hour, take off and land vertically, rotate 
about one point, and fly backward. It also is claimed that this type of airship 
will displace conventional airship and sea-going vessels for mass passenger 
travel in less than 100 years. 

Recent interest in West Germany has centered around the efforts of 
Theodor Wullenkemper , who in 1972 built a 6000 cu m (212, 000 cu ft) non-rigid 
airship at a reported cost of £625, 000. Reportedly, a second and possibly a third 
airship of similar description has flown, with one airship about to fly with the 
third sold to a Japanese firm. The initial Wullenkemper airship was very 
similar to the Goodyear advertising airships. 

Projected details regarding Wullenkemper airship configurations are given 
in Table 26. Reportedly, the airships will see a wide variety of commercial 


- 141 - 



TABLE 26 - TECHNICAL DETAILS OF PROPOSED (AND EXISTING) 
WULLENKAMPER NON-RIGID AIRSHIPS* 


Detail 

WDL 1 
experi - 
mental 

WDL 2 
experi- 
mental 

WDL 3 
experi- 
mental 

WDL 4 
commercial 
design 

Expected completion 

1971 

1972 

1973 

? 

Volume (m^ helium) 

6, 000 

13, 000 

20, 000 

64, 000 + 

Length (m) 

55 

70 

80 

120 

Max diameter (m) 

14. 5 

18 

20 

28 

Gross weight (kg) 

6, 300 

13, 650 

21, 000 

21, 000 
(65, 000? ) 

Useful load (payload kg) 

1,500 

5, 000 

10, 000 

30, 000 

Useful load (payload tons) 

(1.5) 

(4.5) 

(9) 

(30) 

Envelope weight (kg) 

1,600 

3, 200 

4, 500 

11, 000 

Power Plant (hp) 

2 x 180 

2 x 350 

2 x 400 

2 x 700 

Max speed (kmh) 

100 

120 

140 

140 

Range (operating radius)(km) 

400 

— j 

1, 000 

1, 800 

2, 600+ 


*1.0 cu ft = 2.832 X lO'^cu m, 1 . 0 ft = 3 . 048 X 1 0" 1 m, 1 . 0 lbm = 4 . 536 X 1 0“ } kg, 
1 HP - 7.457 X 10 watts, 1 mi = 1.609 km 


uses including passenger transport, heavy load transport, and rescue operations 
and will use a stable platform for scientific observation and military surveillance. 
Reportedly, Wullenkemper has recently applied for a permit to erect a permanent 
hangar for building additional larger airships. 

Two French configurations are of some interest and are briefly described 
below. The Obelix Flying Crane consept uses existing equipment and specific- 
ally is a heavy-lift, reasonably short-haul vehicle. It uses four balloons, each 
with nearly 743, ZOO cu m (8, 000, 000 cu ft), to which eight helicopter rotors are 
attached by means of a support structure. The responsible French design team 
believes such a vehicle could be flying by 1980 if started in 1975. The team has 
determined that three such vehicles could be used in France and 10 additional 
units in the remainder of Europe. 

The second French configuration of some interest is again a flying saucer- 
shaped vehicle Z34. 70 m (770 ft) in diameter, with a volume of about 9. Z9 X 10^ 
cu m (100, 000, 000 cu ft). 

- 142 - 











REFERENCES 


1. Development and Present Status of German Airships; Automotive 

Industries, May 19, 19^1; Goodyear Aerospace Corporation Library 
Control Number L01065 

Z. Stahl, Fredrick; Rigid Air ships ; Technical Memorandum, National 
Advisory Committee for Aeronautics, No. Z37; Goodyear Library 
Control Number 44Z3 

3. Durand, W.F. (Chairman, Special Committee on Airships); Review and 
Analysis of Airship Design and Construction Past and Present; Report 
Number Z, January 30, 1937; Goodyear Aerospace Corporation Library 
Control Number L01065 

4. Vorachek, J.J; Investigation of Powered Lighter-Than-Air Vehicles; 

Report Number AFCRL- 68- 06Z6; Novermber Z7, 1968 

5. Smith, R.K.; An Inventory of U.S. Army Airships With Miscellaneous 
Characteristics, Performance and Contract Data, 1916“ 1961 

6. Data from Goodyear Aerospace Files Assimilated from Various German 
Weight Reports; Final Weight Statement of Macon Document and 1944 
Design Analysis for 10, 000, 000 Cu Ft Airship 

7. The Metalclad Airship ZMC-Z, Aircraft Development Corporation (Division 
of Detroit Aircraft Corporation); Goodyear Aerospace Corporation Library 
Control Number L01065 

8. Brooks, P . W .; Historic Air ships 

9. Burgess, C.P.; Compari son of W eights of U . S . S . Akron and the M C - 74 ; 
Design Memorandum 1935; August 1933 

10. Burgess, C.P.; The Ultimate Airship, Design Memorandum Z74; 

August 1937 

11. Rosendahl, C.E., VAdm, USN (Ret); Where Do We Go From Here; 
Proceedings from the Interagency Workshop on Lighter Than Air Vehicles; 
September 1974 

1Z. Nobile, Umberto, General; Navigating the "Norge" from Rome to the 
North Pole and Beyond; Goodyear Aerospace Library Control Number 
L01056 

13. Actual Weight and Balance Report Model ZPG-3W Airship; Goodyear 
Aerospace Report GER 9639, February 15, I960 


143 - 



14. Clay, Eugene; Historic Highlights of Rigid Airships; Address Delivered 
Before The Historical Branch of The Institute of Aeronautical Sciences 
at Los Angeles, California, September 28, 195 1. Goodyear Aerospace 
Corporation Library Control Number L00573. 

15. Hovgaard, W. ; Memorandum on Preliminary Survey of the History of 
Airships (Prepared for Doctor Durand, Chairman Committee on Airship 
Design and Construction); April 1935; Goodyear Aerospace Library 
Control Number L01106 

16. Lehmann, E. A. ; The Safety of the Zeppelin Airship; Presented at 
ASME Meeting, New York, 1925 

17. Austrotas, R. A. ; Basic Relationships for LT A Economic Analysis; 
Proceedings from the Interagency Workshop on Lighter Than Air 
Vehicles; September 1974 

17A. High Spots in History of Rigid Airships in the Navy; July 26, 1930; 
Goodyear Aerospace Library Control Number L01066 

18. Burgess, C.P.; The Longitudinal Strength of Rigid Airships 
(Design Memorandum No. 261), July 1944 

19- Karman,T.V. and T roller, T, ; Summary Report of the Investigations 
of Gust Effects on Airships, Daniel Guggenheim Airship Institute, 

Akron, Ohio, March 1941 

20. Daniel Guggenheim Airship Institute Report on Water Model Tests, 
February 1940 

21. Daniel Guggenheim Airship Institute Report on Water Model Tests, 

April 1943 

22. 1973/1974 Aerospace Facts and Figures; Aerospace Industries 
Association of America 

23. Kuethe, A. M. ; A Water Tank for Model Tests on the Motion of Airships 
in Gusts, Journal of the Aeronautical Sciences, Vol. 5, No. 6 

April 1938 

24. Calliguos, J.M. and McDavitt, P.W.; Response and Loads on Airships 
due to Discrete and Random Gusts, MIT Aeroelastic and Structures 
Research Laboratory, Technical Report 72-1, February 1958 

25. Rosendahl, C.E. ; The Mooring and Ground Handling of a Rigid Airship; 
Aeronautical Engineering ( January-March 1933) 


- 144 - 



26. Bolster, C.M.; Mechanical Equipment for Handling Large Rigid Airships, 
Aeronautical Engineering, ( July-September 1933) 


27. Handbook, Airship Ground Handling Instructions, NAVWEPS 01-1F-501, 
Goodyear Aerospace Corporation Library Control Number 44607 

28. Kline, Capt; Airship Thesis; Air War College, Marwell Air Force 
Base, 1957 

29. Mowforth, E.; The Airfloat HL Project; Proceedings from the Interagency 
Workshop on Lighter Than Air Vehicles; September 1974 

30. Piasecki, F.N.; Ultra-Heavy Vertical Systems - The "Heli-Stat"; 
Proceedings from the Interagency Workshop on Lighter Than Air Vehicles; 
September 1974 

31. Parametric Study of Dynamic Lift Aerostats for Future Naval Missions, 
Goodyear Aerospace Document Number GER-13564; January 31, 1968 

32. Havill, C. and Harper, M.; A Semibuoyant Vehicle for General Trans- 
portation Missions; Proceedings from the Interagency Workshop on 
Lighter Than Air Vehicles; September 1974 

33. Pake, F.A, and Pipitone, S. J.; Boundary Layer Control for Airships; 
Proceedings from the Interagency Workshop on Lighter Than Air Vehicles; 
September 1974 

34. Silent Joe II Final Report; Goodyear Aerospace Report Number GER- 14328 
May 14, 1969 

35. Miller, W. Jr.; The Dynairship; Proceedings from the Interagency 
Workshop on Lighter Than Air Vehicles; September 1974 


- 145 - 




Reproduced by NTIS 

National Technical Information Service 
U.S. Department of Commerce 
Springfield, VA 22161 


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